The lambda probe does not work. What you need to know about lambda (oxygen sensor)

13.10.2019

The efficiency of a car engine depends on the quality of combustion of the gas-air mixture. The exact proportions, and accordingly the rational effect of the work, is regulated by an oxygen sensor - a lambda probe. Understanding the design and principle of operation of the device is necessary for self-identification and correction of defects. The safety of operating your own car depends on how quickly the causes / consequences of a malfunction of the lambda probe are identified and eliminated.

Only cars with injection engines are equipped with the sensor. Location in the exhaust pipe after the catalyst. A dual-package oxygen sensor can be located upstream of the catalyst, providing enhanced control over the composition of the gas, thereby ensuring more efficient operation of the device.

Operating principle:

The electronics of the car, which is responsible for the dosage of fuel, sends a signal about the demand for supply to the nozzle.
Accordingly, the oxygen device determines the right amount of air to form the correct mixture.
The device settings allow you to meet the requirements for the environmental and economic component of the issue of car operation - to eliminate excessive fuel consumption and gas contamination of the environment.

Modern cars are equipped with progressive devices - catalysts and paired sensors - that allow reducing the negative effects of exhaust emissions and the consumption of expensive fuel and lubricants. However, in the event of a breakdown of an expensive version of the sensor, the “treatment” will cost a considerable amount.

The design of the lambda probe

Externally, the device looks like a steel elongated body-electrode with output wires and platinum coating. Inside the device is the following:

A contact that connects wires to an electrical element.
Sealing dielectric cuff for safety with a hole for air inlet.
Hidden zirconium electrode enclosed in a ceramic tip heated by current up to 300-1000 degrees.
Protective temperature shield with exhaust gas outlet.

Sensors are either point-to-point or broadband. The classification of devices does not affect the external and internal device, however, it has a significant difference in the principle of operation. The device described above is a two-point device, the second is a modernized version.

More about him:

In addition to the two-point design, the sensor also contains an injection element. The meaning of the work is that when the constant voltage fluctuates between the electrodes, a signal is sent to the control unit. The supply of current to the pumping element increases or decreases, a portion of air enters the gap for analysis, where the level of concentration of exhaust vapors is determined.

Symptoms of a lambda probe malfunction

Eternal, created by human hands - does not exist. Any technique designed for fine analysis can fail for many reasons. Oxygen sensors are no exception.

Let's consider in detail:

Increased CO level. It is possible to determine the concentration on your own, only with the help of instruments. Almost always, the indicators indicate a malfunction of the probe.
Increased fuel consumption. Injection cars are equipped with a scoreboard that indicates the amount of fuel consumed. Also, an increase can be judged if the frequency of refueling exceeds the usual.
The light signaling, oriented towards the operation of the lambda probe, is constantly on. This is the Check Engine light.

In addition to the described signs of destabilization of the oxygen sensor, the quality of the exhaust gas can be assessed visually - light smoke indicates oversaturation of the air in the mixture, clouds of thick black smoke, on the contrary, indicate excessive fuel consumption.

Causes of failure of the oxygen sensor

Since the device directly works with the products of fuel combustion, its (fuel) quality cannot but affect the productivity and result. A combustible product that does not meet all established GOSTs and regulations often serves as the root cause why the sensor does not show reliable results or, in general, fails. Lead is deposited on the surface of the electrodes, making the lambda probe insensitive to detection.

Other reasons:

Mechanical failure. From vibration and / or active operation of the car, the sensor housing is damaged. The device is not subject to repair or replacement of components. It would be much more rational to purchase and install a new one.
Incorrect operation of the fuel system. Over time, the soot formed as a result of incomplete combustion of the fuel settles on the body, gets inside the probe inlets. The readings are getting wrong. The problem is initially stopped by timely cleaning, however, if it occurs constantly, then it will not be possible to get rid of it - the oxygen sensor is a consumable item that must be replaced in a timely manner.

In order to achieve the health of the car at all its nodes, it is important to send your own “horse” for periodic diagnostics to identify problems. Then, the functionality of the devices, including the lambda probe, will be preserved.

How to independently check the lambda probe for serviceability

A reliable result about the cause of the breakdown can only be given by qualified diagnostics. However, it is possible to understand that the sensor is faulty on your own. For this:

Learn the manual. The attached instruction to the device contains the parameters of the oxygen sensor. It is important to focus on them.

Having opened and examined the engine compartment, they find a probe. External contamination in the form of soot and / or light deposits will indicate the deposition of lead and abnormal operation of the fuel system. In this case, the device is completely changed and other components of the car are diagnosed, since the ingress of dirt and heavy metal on them does not bode well.
If the tip is clean, the test continues. To do this, the sensor is disconnected and connected to a voltmeter. The car is started, increasing the speed to 2500 / min and reducing to 200. The readings of the working sensor vary in the range of 0.8–0.9 W. No response or lower values indicate a malfunction.

You can also check the probe using a lean mixture, provoking suction in the vacuum tube. In this case, the readings of the voltmeter with a working device are low - up to 0.2 W and below.

The dynamic performance of a 0.5 W sensor connected to the fuel supply system in parallel with a voltmeter indicates that the device is working. Other values will indicate a malfunction.

Do-it-yourself oxygen sensor trick

Without delaying regular inspection - in particular, for a lambda sensor, it occurs every 30 thousand km - the owner of the car ensures the uninterrupted operation of the device. After 100 thousand km, he needs a complete replacement.

If everything is in order with a conscientious attitude towards the car, then it will not be possible to control the quality of the fuel. As a result, carbon deposits or lead deposits will cause the Check Engine light to be constantly responsive. So that this does not bother the car owner, the problem is solved with the help of a snag.

Construction types

Depending on financial capabilities, they make bronze spacer parts with their own hands, buy technological electronic options, arrange a flashing of the entire control unit. Let's describe each method in detail:

homemade device

The body is a bronze piece with high temperature resistance. The dimensions are strictly coordinated with the sensor, in order to avoid leakage of exhaust fumes. The hole for their exit into the spacer is not more than 3 mm.

The principle of operation of the device is as follows: the ceramic crumb inside the cylinder, covered with a layer of catalyst, is oxidized under the action of exhaust gas and oxygen, which causes the concentration to decrease, and the sensor takes the value as normal. The option is budgetary, however, it is unacceptable for cars of a high price category - in the end, automation should work for the result.

Electronic snag

Specialists in soldering circuits can "bundle" a snag for an oxygen sensor with their own hands. This requires a capacitor or resistor. That motorist, whose knowledge is limited, cannot use the method - a misunderstanding of the processes threatens to negatively affect the entire control unit. To solve the problem, a ready-made design is purchased. The principle of operation of the emulator with a microprocessor is as follows:

The microcircuit evaluates the gas concentration and analyzes the signal from the first sensor.
After that, it generates an impulse corresponding to the signal from the second one.
As a result, average readings are obtained that do not affect the normal operation of the control unit, since the input value is always less than the critical value.

flashing

To deceive the oxygen lambda sensor, possibly with the help of a cardinal flashing of the control unit. The bottom line is the lack of response to a signal after the catalyst - the sensor only responds to the state of the unit installed in front of the catalyst, that is, where there are no exhaust vapors or there is a small amount that does not affect the result of the analysis.

Attention! Warranty services will refuse to do the work, as this is contrary to the normal maintenance of the car - any node must work and respond to emergency situations.

This is especially true for new cars. Therefore, the firmware is purchased independently - in no case via the Internet - or installed from home-grown craftsmen. Otherwise, the damage caused to the car in the future should not cause confusion for the owner of the car.

Video review of tricks

We determine the malfunction of the lambda probe video

Modern vehicles are equipped with many sensors that monitor the performance of components and assemblies. One of the main vehicle sensors is the residual oxygen sensor (λ-probe). However, only a few motorists know how to check the lambda probe on their own, saving time and money.

What is a lambda probe and where is it located

In connection with the tightening of environmental standards to reduce the toxicity of exhaust gases, cars began to be equipped with a catalytic converter (catalyst). The quality and duration of its operation is directly dependent on the composition of the fuel-air mixture (FA). Depending on the signals transmitted by the lambda probe, the percentage ratio in the mixture of fuel and air is regulated.

Lambda probe - a system that determines how much residual oxygen is contained in the exhaust gases. Otherwise, it can be called an oxygen sensor.

The lambda probe is located in the exhaust manifold in front of the catalytic converter

High-quality purification from toxic exhausts in the catalyst is carried out only in the presence of oxygen in them. To control the effectiveness of the converter and improve the accuracy of studying the state of exhaust gases, many models install a second lambda probe at the catalyst outlet.

To improve efficiency on modern cars, an additional lambda probe is installed at the catalyst outlet.

How an oxygen sensor works

The main function of the lambda probe is to measure the amount of oxygen contained in the exhaust gases and compare it with the reference.

Electrical impulses from the oxygen sensor are sent to the electronic control unit (ECU) of the fuel system. With respect to these data, the ECU regulates the composition of the fuel assemblies supplied to the cylinders.

Scheme of installation of the main and additional oxygen sensors in the car

The result of the joint work of the lambda probe and the ECU is to obtain a stoichiometric (theoretically ideal, optimal) fuel assembly, consisting of 14.7 parts of air and 1 part of fuel, at which λ=1. For an enriched mixture (excess gasoline) λ<1, у обеднённой (избыток воздуха) - λ>1.

Graph of power (P) and fuel consumption (Q) versus value (λ)

Varieties of lambda probes

Modern cars are equipped with the following sensors:

Zirconia;
titanium;
Broadband.

Zirconia

One of the most common models. Formulated with zirconia (ZrO2).

The zirconium oxygen sensor operates on the principle of a galvanic cell with a solid electrolyte in the form of zirconia ceramic (ZrO2)

The ceramic tip with zirconium dioxide is covered on both sides with protective screens of conductive porous platinum electrodes. The properties of an electrolyte permeable to oxygen ions appear when ZrO2 is heated above 350°C. The lambda probe will not work without warming up to the desired temperature. Fast heating is carried out due to the heating element built into the body with a ceramic insulator.

Important! Raising the temperature of the sensor to 950°C leads to its overheating.

Exhaust gases enter the outer part of the tip through special gaps in the protective casing. Atmospheric air gets inside the sensor through a hole in the housing or a porous waterproof sealing cover (cuff) of the wires.

The potential difference is formed due to the movement of oxygen ions through the electrolyte between the outer and inner platinum electrodes. The voltage generated across the electrodes is inversely proportional to the amount of O2 in the exhaust system.

The voltage that develops across the two electrodes is inversely proportional to the amount of oxygen

Regarding the signal coming from the sensor, the control unit regulates the composition of the fuel assembly, trying to bring it closer to the stoichiometric one. The voltage coming from the lambda probe changes several times every second. This makes it possible to regulate the composition of the fuel mixture, regardless of the mode of operation of the internal combustion engine.

By the number of wires, several types of zirconium devices can be distinguished:

In a single wire sensor, there is only one signal wire. Ground contact is made through the housing.
The two-wire device is equipped with signal and ground wires.
Three- and four-wire sensors are equipped with a heating system, control and ground wires to it.

Zirconium lambda probes, in turn, are divided into one-, two-, three- and four-wire sensors

titanium

Visually similar to zirconia. The sensitive element of the sensor is made of titanium dioxide. Depending on the amount of oxygen in the exhaust gases, the volume resistance of the sensor changes abruptly: from 1 kOhm with a rich mixture to more than 20 kOhm with a poor one. Accordingly, the conductivity of the element changes, which the sensor signals to the control unit. The operating temperature of the titanium sensor is 700°C, so a heating element is required. Reference air is missing.

Due to its complex design, high cost and finicky to temperature changes, the sensor has not received wide distribution.

In addition to zirconium, there are also oxygen sensors based on titanium dioxide (TiO2)

Broadband

Structurally different from the previous 2 chambers (cells):

Measuring;
Pumping.

In the chamber for measurements using an electronic voltage modulation circuit, the gas composition corresponding to λ=1 is maintained. The pump cell, when the engine is running on a lean mixture, removes excess oxygen from the diffusion gap into the atmosphere, when the mixture is rich, it replenishes the diffusion hole with the missing oxygen ions from the outside world. The direction of the current for moving oxygen in different directions changes, and its value is proportional to the amount of O2. It is the value of the current that serves as the detector λ of the exhaust gases.

The temperature required for operation (at least 600°C) is achieved due to the operation of the heating element in the sensor.

Broadband oxygen sensors detect lambda from 0.7 to 1.6

Malfunction symptoms

The main signs indicating a breakdown of the oxygen sensor are:

Increased toxicity of exhaust gases;
Unstable, intermittent acceleration dynamics;
Short-term switching on of the "CHECK ENGINE" lamp with a sharp increase in speed;
Unstable, constantly changing idle;
Increased fuel consumption;
Overheating of the catalyst, accompanied by crackling sounds in its zone when the engine is turned off;
Constantly burning indicator "CHECK ENGINE";
Unreasonable signaling of the on-board computer about over-enriched fuel assemblies.

It must be borne in mind that all these deviations can be symptoms of other breakdowns.

The service life of a lambda probe is approximately 60-130 thousand km. The reasons for the reduction of the service life and breakdown of the device may be:

The use of sealants (silicone) during the installation of sensors that are not designed for high temperatures;
Low-quality gasoline (high content of ethyl, lead, heavy metals);
Oil entering the exhaust system as a result of wear of oil scraper rings or caps;
Overheating of the sensor as a result of incorrectly set ignition, over-enriched fuel assemblies;
Multiple attempts to start the engine, leading to the penetration of combustible mixtures into the exhaust system;
Unstable contact, short to ground, broken output wire;
Violation of the integrity of the sensor design.

Methods for diagnosing an oxygen sensor

Experts advise checking the correct operation of the lambda probe every 10,000 km, even if there are no problems in the operation of the device.

Diagnostics begins with checking the reliability of the connection of the terminal with the sensor and for the presence of mechanical damage. Next, unscrew the lambda probe from the manifold and inspect the protective cover. Small deposits are cleaned.

If, during a visual inspection, traces of soot, heavy white, gray or shiny deposits were found on the protective tube of the oxygen sensor, the lambda probe should be replaced

How to check a lambda probe with a multimeter (tester)

Checking the sensor for performance is carried out according to the following parameters:

Voltage in the heating circuit;
"Reference" voltage;
Heater status;
Sensor signal.

Wiring diagram for a lambda probe depending on its type

The presence of voltage in the heating circuit is determined with a multimeter or voltmeter in the following sequence:

Without removing the connector from the sensor, turn on the ignition.
The probes are connected to the heating circuit.
The readings on the device must match the voltage on the battery - 12V.

"+" goes to the sensor from the battery through the fuse. In its absence, this chain is called.

"-" comes from the control unit. If it is not detected, check the terminals of the lambda probe - ECU circuit.

Measurements of the reference voltage are carried out by the same devices. Sequencing:

Turn on the ignition.
Measure the voltage between the signal wire and ground.
The device should show 0.45 V.

To check the heater, the multimeter is set to ohmmeter mode. Diagnostic steps:

Remove the connector from the device.
Measure the resistance between the heater contacts.
The readings on different oxygen tanks are different, but should not go beyond 2-10 ohms.

Important! The absence of resistance indicates a break in the heater circuit.

A voltmeter or multimeter is used to check the sensor signal. For this:

Start the engine.
Warm it up to operating temperature.
The probes of the device are connected to the signal wire and the ground wire.
The engine speed is increased to 3000 rpm.
Monitor voltage readings. Jumps should be observed in the range from 0.1 V to 0.9 V.

If during at least one of the checks the indicators differ from the norm, the sensor is faulty and needs to be replaced.

Video: checking the lambda probe with a tester

The main advantage of this lambda probe diagnostics over checking with a voltmeter and multimeter is the fixation of the time between the same type of output voltage changes. It should not exceed 120 ms.

Sequence of actions:

The probe of the device is connected to the signal wire.
The motor is warmed up to operating temperature.
The engine speed is increased to 2000-2600 rpm.
According to the oscilloscope, the performance of the oxygen sensor is determined.

Diagnostics with an oscilloscope gives the most complete picture of the operation of the lambda probe

Exceeding the time indicator or crossing the voltage limits of the lower 0.1 V and the upper 0.9 V indicates a faulty oxygen sensor.

Video: oxygen sensor diagnostics with an oscilloscope

Other verification methods

If the car has an on-board system, then the “CHECK ENGINE” signal, which gives a certain error, can be used to diagnose the state of the lambda probe.

List of lambda probe errors

In order for the lambda probe to work for a long time and efficiently, it is necessary to fill the car with only high-quality fuel. Scheduled and timely diagnostics of the oxygen sensor will help to detect its malfunction in time. This measure can extend the life of not only the sensor itself, but also the catalyst.

The lambda probe is an O 2 concentration sensor (or, more simply, an oxygen sensor), which allows you to estimate the amount of unburned oxygen contained in the exhaust gases. These indicators are extremely important, because due to the maintenance of certain proportions of fuel and air, the most efficient combustion of the air-fuel mixture occurs. The best ratio is considered to be 14.7 parts of oxygen to 1 part of gasoline. If this ratio is violated, then the mixture will be poor or, conversely, enriched, which, in turn, will affect fuel consumption and engine power.

Although outwardly the oxygen sensor does not look like a "vital" part, it performs a very important function, so any malfunction of the lambda probe, the "symptoms" of which we will consider, should be immediately corrected.

Signs and causes of a malfunctioning lambda probe

According to statistics, oxygen sensors fail gradually, so you can identify its malfunction if you pay attention to the following “symptoms” in time:

The idle speed started to drop or "float".
The car twitches, and after starting the engine, claps uncharacteristic of the engine are heard.
The engine power has decreased and when you press the gas pedal, a slow reaction is observed.
The engine is overheating and fuel consumption has increased.
The smell in the exhaust pipe has changed (exhaust gases have become more toxic).

As a result of a failed sensor, the quality of the fuel mixture entering the combustion chamber deteriorates, which disrupts the smooth operation of the engine. There can be many reasons for this:

Incorrect operation of the filament circuit or reduced sensitivity of the sensor tip.
Low quality fuel with a high content of iron, lead, oil decay particles and other harmful inclusions. All these substances adhere to the platinum electrodes, which leads to a malfunction of the sensor.
Problems with the lambda probe heating system. If the heating stops functioning as it should, the oxygen sensor will give inaccurate data.
Overheating of the regulator housing. This happens if the ignition timing is set incorrectly.
Worn oil scraper rings. In this case, motor fluid enters the exhaust pipe, which acts on the lambda probe.
If the engine is started repeatedly.
The use of sealants (especially silicone) to install lambda probes.
The compression level in the engine cylinders is broken. In this case, the combustible mixture burns unevenly.
Clogged fuel injectors.

If you notice that the lambda probe is not working, the symptoms should not be ignored, otherwise you will provide yourself with many problems with the car. The fact is that most modern cars are equipped with an emergency blocking unit that can work at the most unfortunate moment. However, the impossibility of further movement is not the worst thing. If the sensor is depressurized, then the injection system will fail and you will have to pay for expensive repairs to a more serious unit.

Checking the oxygen sensor

Usually, the lambda probe is diagnosed using a voltmeter and an ohmmeter or a multimeter, which replaces both of these testers at once. To check the filament coil of the regulator, it is necessary to disconnect pins 3 and 4 of the connector from the block (usually these are brown and white wires) and connect the ends of the tester to their clamps. If the resistance of the spiral is at least 5 ohms, then this is a good sign.

Also, checking the lambda probe with a multimeter allows you to find out the sensitivity of the oxygen sensor tip. To find out the thermoelectric parameters of the element, it is necessary to turn on and warm up the engine to 70-80 degrees. After that:

Bring the engine speed to 3000 and hold this figure for 3 minutes to warm up the sensor.
Connect the negative probe of the tester (signal wire) to the ground of the machine, and the second one to the output of the lambda probe.
Check the tester readings, the data should range from 0.2 to 1 V and be updated up to 10 times per second.
Press the accelerator pedal sharply and release it, if the multimeter shows a value of 1 V, and then drops sharply to zero, then the lambda probe is in order. If the data on the tester does not jump when the pedal is pressed and released, and the indicators are about 0.4 - 0.5 V, this indicates the need to replace the sensor.

If there is no voltage at all, then most likely the cause of the malfunction lies in the wiring, so “ring out” with a multimeter all the wires that go from the ignition switch to the relay.

Healthy! To more accurately clarify the sensitivity characteristics of the lambda probe, you will need professional equipment - an oscilloscope.

If your car is equipped with a "smart" on-board system, then pay attention to the "Check Engine" signal, which can give the following errors:

0130 - indicates that the sensor is giving an incorrect signal.
0131 - very weak sensor signal.
0133 - lambda responds slowly.
0134 - no response at all.
0135 - malfunction of the lambda heater.
0136 - grounding of the second sensor is shorted.
0137 - the second sensor produces a very low signal.
0138 - too high signal of the second lambda.
0140 - probe break.
1102 - it is impossible to read the indicators, since the resistance of the element is too low or completely absent.

However, before checking the lambda probe oxygen sensor (the video of this process is presented below) using a special tester, pay attention to its appearance. If substances that interfere with its full-fledged work have stuck to it, then it may be possible to confine itself to repairing this element.

How to repair a lambda probe

Do-it-yourself lambda probe repair is quite simple, for this you need to determine which node failed.

If the problem is related to the contacts of the circuit, then first of all it is necessary to find the place of the break and check if the contacts have oxidized. The signal may, elementarily, not come from the control unit. Therefore, check the power supply of the lambda. If the contacts of the element are oxidized, they must be treated with WD40.

If there is a lot of carbon build up on the probe body, cleaning of all parts of the system may be required. And then a logical question arises, how to rinse the lambda probe. The fact is that it is strictly forbidden to process platinum electrodes and a ceramic rod with sandpaper. Therefore, it is necessary to use specialized products designed to dissolve rust.

To clean the sensor, follow these steps:

Dismantle the lambda probe, preheating its body to 50 degrees.
Remove the protective cap.
Soak the sensor in phosphoric acid for 30 minutes (it will tackle even the toughest deposits).
Rinse the lambda in water, dry and install the element back. Remember to lubricate the sensor threads with a special agent to create a complete seal (but do not use silicone sealant).

Since the cost of sensors ranges from 1000 - 3000 rubles per element, it is quite reasonable to try to repair the lambda probe with your own hands (see video below), and only then proceed with the installation of a new element.

In custody

Car systems are very sensitive and need constant diagnostics and preventive maintenance. In order for lambda probes and other elements to work properly, do not save on good fuel, because most often it is low-quality gasoline that leads to the rapid failure of important working elements.

Lambda probe is a device that recognizes the composition of exhaust gases in order to control the nature of the conversion of fuel in the engine. This is a multi-component device, its components are made of heat-resistant materials. The device is installed in front of the exhaust system catalyst, and it starts to function at a high temperature. Sometimes there are two sensors - before and after the catalyst.

As the device heats up, an output voltage appears on its electrodes. Then the lambda probe measures the residual oxygen in the exhaust gases of the car. If its value deviates from the norm, a signal is sent to the ECU, which restores the composition of the fuel-air mixture.

Blende- a detail that complements the device, corrects the signal coming from it. There are two types - mechanical(gas passes through it and oxidizes, the amount of oxygen decreases, the ECU receives a more correct value of the indicator) and electronic(supports the operation of the auto power unit adjustment system, analyzes the actual composition of the exhaust, on the basis of which it corrects the signal supplied by the ECU; as a result, the engine operates normally, despite a faulty catalyst or its absence).

The lambda probe can be narrowband and broadband. In the first case, it is able to analyze only standard voltage values, which can lead to engine malfunctions due to incorrectly changed fuel concentration in the fuel mixture. Wide-band consists of two-point and pumping elements; receives oxygen from the exhaust system under the influence of current; keeps a constant voltage between the electrodes, and if it grows, a signal is sent to the computer; after that, the unit adjusts the composition of the fuel mixture.

Scheme of operation of a narrow-band lambda probe

The difference between a broadband probe and a narrowband probe in that it measures the concentration of oxygen in the exhaust gases at any engine speed. Its range is from 0 to 5 volts. In narrowband, it is only 0-1.

Oxygen sensor works on 50000-100000 km of run. If you pour low-quality gasoline into the tank several times, the sensor may fail almost immediately.

If the lambda probe heating does not work, the device will not feel problems with the composition of the fuel mixture. And the engine will work with increased load, and the toxicity of exhaust gases will increase dramatically. So is fuel consumption.

Damage consequences: the engine will begin to function unstably even at idle, fuel consumption increases, poor purification of exhaust gases by the catalyst becomes worse; the car moves jerkily, does not obey well; motor power is reduced.

How to understand that the device is broken: the car in motion starts to twitch; uncharacteristic sounds are heard from under the hood; the indicator on the dashboard is lit; engine power drops, and the accelerator pedal works more slowly; a sharp and unpleasant smell appears from the exhaust pipe; the motor is overheating. With a complete failure of the car, it may not go.

Read more in our article on how the lambda probe works.

Read in this article

What is a lambda probe

In modern cars, a lot of sensors are installed, which not only allow you to better control the operation of its various systems, but also increase environmental safety. One of the devices is a lambda probe. The device recognizes the composition of the exhaust gases in order to control the nature of the fuel conversion in the engine.

If the ratio of fuel and air is no longer optimal, the sensor informs the electronic control unit of the injection system. He brings the composition of the mixture back to normal by reducing or increasing the volume of fuel supplied.

How does a lambda probe work in a car

To understand how a lambda probe works in a car, you need to understand what it is made of. This is a multi-component device, its components are made of heat-resistant materials. The device is installed in front of the exhaust system catalyst, and it starts to function at a high temperature. Sometimes there are two sensors - before and after the catalyst.

As the device heats up, an output voltage appears on its electrodes. And the lambda probe acquires the ability to measure the residual oxygen in the exhaust gases of a car. If its value deviates from the norm, a signal is sent to the ECU, which restores the composition of the fuel-air mixture.

What is a scam and why is it needed?

One of the breakdowns may affect the exhaust system catalyst, after which the exhaust gas emission increases. It can be removed or replaced with a flame arrester. But the engine starts to work in emergency mode due to an incorrect signal from the lambda probe.

A cheat can save you from this. The part complements the device, corrects the signal coming from it. There are two types of cheats:

Mechanical. The gas passes through such a part and is oxidized. As a result, the volume of oxygen decreases, the ECU receives a more correct value of the indicator. The system is given information in the form in which it occurs with a properly functioning catalyst.
Electronic. This is a more complex device based on a microprocessor. This is how the snag of an electronic type lambda probe works: it supports the operation of the auto power unit adjustment system, analyzes the actual composition of the exhaust, on the basis of which it corrects the signal supplied by the ECU. As a result, the engine operates normally, despite a faulty catalyst or its absence.

Scheme for connecting electronic snag

What does broadband mean

Devices are narrowband and broadband. In the first case, they are able to analyze only nominal voltage values. That is, information transmitted at low engine speeds. Everything else reads with an error, and the computer receives a not quite correct signal. This can lead to engine malfunctions due to incorrectly changed fuel concentration in the fuel mixture.

How a broadband lambda probe works:

consists of two-point and pumping elements;
thanks to this structure, it receives oxygen from the exhaust system under the influence of current;
keeps a constant voltage between the electrodes, and if it grows, a signal is sent to the computer;
after that, the unit adjusts the composition of the fuel mixture.

Scheme of operation of a broadband oxygen sensor

The difference of the broadband probe is that it measures the concentration of oxygen in the exhaust gases at any engine speed. Its range is from 0 to 5 volts. In narrowband, it is only 0-1.

Does the lambda probe work without a catalyst

The failure of the exhaust system catalyst (exhaust gas purifier) is one of the frequent problems that cause difficulties with the operation of the engine. This happens if there are two controlling sensors: one is installed in front of the device, and the other after it.

In this case, the oxygen content in the exhaust passing through the catalyst will change. This will detect the sensor behind it. He will transmit a false signal to the ECU about the need to correct the composition of the fuel mixture. And in this case, the answer to the question of whether the lambda probe works without a catalyst is negative. After all, he gives a signal based on distorted information. Here you need to put a trick.

Another option is to flash the “brains” of the car, change the catalyst to a flame arrester and remove the sensor. Otherwise, problems with injection will begin, which can lead to high consumption of gasoline, increased engine load, and breakdown.

The oxygen sensor in some cars is located just in front of the catalyst. Then the lambda probe analyzes the exhaust gases that have not yet passed through the cleaner. That is, the data is not distorted whether the catalyst works or not. With a breakdown of the cleaner, only the amount of toxic gases from the exhaust pipe increases.

How much work in general

The oxygen sensor is one of the most sensitive parts of the car. It is enough for 50,000-100,000 km of run. But how long a lambda probe works also depends on:

car operating conditions;
engine health;
type of device (unheated, heated, glider);
fuel quality.

The last factor is especially important. If you pour low-quality gasoline into the tank several times, the sensor may fail almost immediately.

Watch this video on how the lambda probe works:

If the heating does not work

The oxygen sensor begins to analyze the composition of the exhaust after it warms up to 300-400 degrees. If the lambda probe heating does not work, the device will not feel problems with the composition of the fuel mixture. And the engine will work with increased load, and the toxicity of exhaust gases will increase dramatically. So is fuel consumption.

The only way out will be to replace the sensor completely or remove it along with the firmware of the “brain” of the machine.

The consequences of a breakdown

A malfunctioning oxygen sensor will have a detrimental effect primarily on the engine. It will start to function unstably even at idle. When the lambda probe does not work, the consequences are as follows:

Engine power drops, and the accelerator pedal, when exposed to it, works more slowly;

a much sharper and more unpleasant smell appears from the exhaust pipe than before;

the motor is overheating.

From these changes, it is not difficult to understand how a faulty lambda probe works. If it is completely out of order, the car may not go. When the sensor is depressurized, the “brain” of the machine receives many signals about problems, and the injection control system is blocked.

If we talk briefly about how the lambda probe works, it keeps the engine running longer, saves fuel, and reduces exhaust toxicity. It is necessary to regularly check it with a specialist, monitor the quality of the fuel and the engine cooling system. And if the sensor fails, be sure to change it.

Useful video

See this video on how to properly check the lambda probe:

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Replace lambda probe

If the oxygen sensor is faulty, there are several options for solving the problem. One of them is to change the lambda probe sensor. You can do this yourself by buying a new part in a specialized store or car service. Pay attention to the marking that is applied to the old probe. With exactly the same should be a new probe.

If you are not sure that you can handle it, contact the experts. Where can a lambda probe be replaced? In any car service for little money. Experts will do a quality job. The next 50,000-100,000 km, the original oxygen sensor will work perfectly.

Improves engine performance;

A significant disadvantage of this solution is the price. The cost of a new lambda probe reaches 25,000 rubles. If the car has a disabled or knocked out catalyst, replacing the lambda probe will not help. Software shutdown will help - chip tuning.

Clear lambda probe

Soot often accumulates on the oxygen sensor, and combustion products settle inside. This prevents him from working at full capacity. The car loses traction, reduces the maximum speed and increases fuel consumption. One of the solutions to the problem is cleaning the lambda probe.

Orthophosphoric acid cleans the lambda probe in 15-25 minutes. Then rinse the device with warm water and dry thoroughly.

Types of snags on the lambda probe

Disabling lambda probes programmatically using chip tuning will bring nice bonuses:

Increased power and torque;
Reduced fuel consumption (compared to emergency mode);
Improved traction on the bottoms;
The gas pedal will become more responsive;
The overall dynamics of the car will improve, acceleration will become more frisky;
Gear shifts will be smoother;
The operation of the engine with the air conditioner on is optimized, the car will stop “stupid”.

Software deactivation of lambda probes is carried out by ADACT partners in Russia and the CIS countries.

Do not drive with a defective oxygen sensor. The car loses dynamics, fuel consumption increases. Therefore, car owners change, clean, install snags or programmatically disable the lambda probe. Which way is better? We analyzed the pros and cons of each.

Replace lambda probe

Replacement must be done on a cooled engine and the ignition off. To begin with, the wires are disconnected from the old device. Then the old probe is disconnected with a wrench, and a new one is put in its place. You have to be careful not to break the thread.

Benefits of Installing a New Oxygen Sensor

Saves fuel from 5 to 15%. The deterioration of the sensor affects fuel consumption, so installing a new one will return it to normal;
Improves engine performance;
With 100% certainty notifies about the failure of the catalyst;
Reduces the release of harmful substances.

A significant disadvantage of such a solution is the price. The cost of a new lambda probe reaches 25,000 rubles. If the car has a disabled or knocked out catalyst, replacing the lambda probe will not help. Software shutdown will help - chip tuning.

Clear lambda probe

How to clean an oxygen sensor:

Before cleaning the probe, inspect it carefully. If there is damage, or the structure is deformed, then the malfunction is unlikely to be due to contamination. If there is no damage, then the lambda probe can be cleaned.
You will need phosphoric acid, which corrodes scale well and cleans soot. Do not use mechanical cleaning tools: iron brush, sandpaper, file, etc. You will damage the precious metal layer and the sensor will become unusable.
Remove the oxygen sensor from the car and place it in acid. To speed up the process, take a soft brush and apply the liquid evenly over the entire surface.
Orthophosphoric acid cleans the lambda probe in 15–25 minutes. Then rinse the device with warm water and dry thoroughly.

Unfortunately, cleaning does not always help.

If orthophosphoric baths did not bring results, the sensor should be replaced or disabled by software.

Install lambda probe

A broken or malfunctioning oxygen sensor cannot be repaired, but can be replaced with an expensive new one or a snag can be installed. Many car owners choose this simple way to deceive the electronic control unit. At the same time, the snag sends an average (similar to a working) signal to the ECU and the computer thinks that everything is fine. In this case, the whole point of the adaptability of the engine disappears. The computer does not understand how well the mixture is prepared and how environmentally friendly the exhaust is. Without a normal sensor, the ECU goes crazy, which leads to increased fuel consumption and other troubles.

Types of snags on the lambda probe

Mechanical snag on the lambda probe. This universal spare part is installed on almost all cars. Inside it there is a mini-catalyst through which the exhaust gases pass. There they are cleaned a little and the electronic control unit receives underestimated values of harmful emissions.
Electronic snag on the lambda probe. It is specially programmed for a certain brand, volume and year of manufacture of the car, which makes it more expensive than mechanical. Connect the device to the wires through which the values are adjusted to acceptable values.

In both cases, the signals from the first and second oxygen sensors will be different. The ECU will take these readings for the normal operation of the catalyst.

Pros and cons of installing a snag lambda probe

Tricking the lambda probe will turn off the "Check Engine". The cost, compared to other solutions, is small, so this is the most popular procedure.

A snag on a lambda probe, unlike sensor replacement or chip tuning, does not take into account different parameters and engine operating conditions. For example, adjusting the fuel injection. Therefore, during automatic adjustment, the readings after some time will go beyond the limits of conditionally normal error P0140 will come out again and the check will light up.

Disable lambda probe programmatically

After the physical removal of the catalyst, the software shutdown of the lambda probes after it is a mandatory step. Without adaptation, the second sensor located after the catalyst transmits incorrect exhaust values, the check lights up and the engine goes into emergency mode. This is fraught with increased fuel consumption and poor dynamics.