Lambda probe is the traditional name for an oxygen sensor. It controls the amount of oxygen in the exhaust gases. The operation of the engine is directly related to how efficiently the fuel-air mixture burns. And it is oxygen that is largely responsible for the combustion process. By adjusting its content in the mixture, it is possible to control the combustion temperature: by raising or lowering it accordingly. If there is a lot of oxygen in the mixture, then engineers usually denote this situation with the Greek letter lambda. Well, one cannot but agree that the “lambda probe” in Russian sounds much more expressive than the everyday “oxygen sensor”.
The main tasks of the lambda probe
The oxygen sensor is installed where the exhaust gases pass, namely in the exhaust manifold. It is used in those cars that are equipped with an injector. To improve the accuracy of the assessment, two lambda probes are sometimes used. They carefully surround, being on both sides of it.
The electronic control unit regulates the amount of fuel supplied to the engine. An oxygen sensor helps him with this. It transmits information about the oxygen content in the exhaust gases. Depending on the sensor readings, the amount of injected fuel increases or decreases. When there is too much oxygen in the mixture, its combustion temperature rises. In this case, toxic substances are released that are dangerous to humans and the environment. The lambda probe indirectly controls the environmental friendliness of the exhaust system and seeks to create conditions for the proper operation of the catalyst.
Device
There are two types of oxygen sensors: point-to-point and broadband.
Two point sensor has become traditional and is gradually becoming a thing of the past.
It consists of two electrodes: one inside, the other outside. The outer electrode is coated with a thin layer of platinum, which is receptive to oxygen. The electrode located inside is made of zirconium. The potential between the electrodes changes in response to the amount of oxygen in the mixture: the more oxygen, the higher it is.
Broadband sensor an increasingly popular option for the lambda probe.
In this case, two ceramic elements are used. One performs the function of a point-to-point, and the other performs the injection of oxygen. The mixture of exhaust gases no longer simply enters the sensor for evaluation and analysis by itself, but the sensor deals only with oxygen, pumping it separately from the mixture. With a constant voltage of 450 mV, the sensor responds to a decrease or increase in oxygen concentration by changing the voltage, which is immediately informed by the ECU. Having received the appropriate signal, the ECU creates a pumping current. Through the value of the pumping current, the oxygen content in the mixture is determined.
The oxygen sensor only works effectively at temperatures above 300°C, so all lambda probes have a heating system.
Symptoms of the disease
Problems with the lambda probe can manifest themselves as follows.
- The toxicity of exhaust gases has increased and ceased to meet the established standards. However, the motorist himself cannot check this without a special device.
- Increased, but this problem may have many other reasons.
- The engine is idling. Unfortunately, this symptom is also not unambiguous.
- The dynamics of the car is deteriorating.
- In the area of the catalyst, you can hear a characteristic crackling sound.
- The “ ” light came on, but even here it will be necessary to carry out diagnostics in the service center.
Ideally, a breakdown of the lambda probe should be diagnosed by a specialist.
Causes of the malfunction
The lambda probe may fail for the following reasons:
- Poor quality is the first enemy of all sensitive elements developed by foreign engineers in order to take care of the environment. Due to lead deposits, the outer layer of the sensor loses sensitivity and becomes inoperative.
- Mechanical action that violates the design of the lambda probe leads to its breakdown.
- Problems in the fuel system can provoke the formation of soot or soot on all elements of the exhaust system, which interferes with their proper operation.
- Overheating of the sensor can occur for various reasons, but, as with all sensors, too high temperatures have a devastating effect on the lambda probe.
- Ingress or into the exhaust system, as well as its leakage, also leads to a malfunction of the lambda probe.
If the sensor fails, then the ECU loses feedback from the exhaust system and works “blindly”, according to the average parameters that are in its memory. At the same time, it is clear that the composition of the fuel-air mixture, getting out of control, ceases to be optimal.
Lambda probe - vulnerable and relatively short-lived element. In the best scenario, after 60-80 thousand km it fails.
Checking the lambda probe
Almost everyone can check the oxygen sensor. To check, you need to use one or two auxiliary tools: an oscilloscope and a voltmeter. If you do not know where the device is located, then use the manufacturer's instructions.
First, you should check the element for mechanical damage. Its body must be intact, as well as the wiring. If the sensor is not damaged, but dirty, then it is better to replace it with a new one. Of course, carbon deposits and soot, as well as any other plaque, you can try to clean. If it succeeds, good; if not, then replacement is necessary.
Let's assume that our device is not damaged and has a clean surface. Then you should continue checking with a voltmeter or oscilloscope.
When a lambda probe is not needed
The oxygen sensor loses its value after removing the catalyst or replacing it with a flame arrester. In this case, we are talking not only about mechanical removal, but also about software. If it is possible to reprogram the computer, then the need for a lambda probe disappears and you can forget about it. Otherwise, tricks are installed.
It must be said that the lambda probe is not an expensive part (the average price of the part itself varies around 2,000 rubles + 500 rubles for work), so a failed sensor can be completely replaced with a new one. The main thing is to do this in a timely manner, until other elements have suffered, in particular, a catalyst, the price of which is already completely different.
During the operation of the car, various malfunctions occur in the fuel system. You can determine the malfunction by paying attention to the behavior of the car on the road. But first you need to figure out what types of fuel systems are, what components and parts it consists of.
Types of fuel systems
There are diesel and petrol engines. They run on different fuels, respectively, they have different fuel systems.
In diesel engines, fuel from the tank through the pipes is supplied by a fuel priming pump to the injection pump (high pressure fuel pump), then from the injection pump to the injectors. From the injectors, fuel enters the cylinder directly through the engine intake manifold.
There is no such pressure in gasoline engines - gasoline does not need such a high compression ratio to burn gasoline. The fuel systems of gasoline engines vary by type. There is a distributed injection system (injector), a single-point injection system (single injection) and a carburetor. Carburetor engines have recently been discontinued and are living out their last days.
Fuel System Parts
Regardless of the type of engine, any fuel system consists of a fuel pump, fuel pipes and a direct device that supplies fuel to the intake manifold. Such a device is almost always a nozzle; in carbureted engines, this role is played by a carburetor.
In modern engines, sensors are used that affect the quality of the combustible mixture and fuel consumption. As part of the injector and single injection, there is an idle speed controller and a throttle position sensor. The air flow sensor is present in injectors and modern diesel systems. In recent years, an oxygen sensor (lambda probe) has been installed on almost all types of engines.
The device and principle of operation of the oxygen sensor
The oxygen sensor (lambda probe) is located in the car's exhaust system. Depending on the complexity of the design, one or two sensors can be installed, and there are more. If there is one lambda probe, then it is located on the exhaust manifold.
The lambda probe is a ceramic element in a metal case, to which voltage is applied through wires. Ceramics, depending on the qualitative composition of gases in the exhaust system, sends a signal to the control unit. Fuel management is adjusted according to the sensor readings.
What causes an oxygen sensor to fail
The most banal thing that can cause a lambda probe to fail is mechanical damage. Let's say your car has been in an accident. Often, in our Russian conditions, the quality of the fuel is to blame. It's no secret that gasoline at gas stations in Russia is often "bodya".
Poor engine condition affects sensor performance. A faulty piston group throws engine oil into the exhaust system, thereby clogging the ceramics at the "lambda".
An incorrectly adjusted ignition leads to overheating of the sensor. Due to the same ignition, pops may appear in the muffler. Strong pops destroy the lambda probe.
Disables the oxygen sensor antifreeze and brake fluid, which fall on the ceramic insulator. This may be due to fluid leaks in the brake and cooling system.
The main symptoms of lambda probe malfunctions
You can understand whether the oxygen sensor is working or not by some characteristic signs. Although the cause of the problem may be different, professional diagnostics are needed to accurately determine the defect.
A faulty oxygen sensor could be if:
- - the car on the road moves with jerks,
- - increased fuel consumption,
- - the car "stupid", rides badly and picks up speed,
- - the engine runs erratically at idle,
- - immediately after stopping, a characteristic crack is noticeable in the area where the "lambda" is located,
- - during an external examination of the sensor, it turns out that it has heated up to a red-hot state (turned red).
If the wires are broken at the sensor, then there is no doubt - in this state it will not work. In the presence of external damage, one can doubt the operability of the lambda probe.
The Check Engine warning lamp in the passenger compartment also indicates any malfunctions in the engine's electrical system, but a malfunction can only be accurately determined using computer diagnostics.
Oxygen sensor replacement
Replacing a lambda probe on a car is very simple, especially if the sensor is located on the exhaust manifold (it is more convenient to get to it). It is better to change it on a well-heated engine, as the cold metal shrinks, and the sensor often "sticks" to the manifold.
To replace you need:
- - turn off the engine and turn off the ignition,
- - disconnect the wires at the connector,
- - use a wrench (sometimes a socket wrench is required) to unscrew the faulty sensor,
- - screw the new sensor into place until it stops until it stops, but without any extra effort,
- - connect the wires at the connector.
That's it, pretty basic. Now there will be no problems with the new sensor.
The fuel injection system of a car is more economical and efficient than a carburetor. This is achieved through complete control over the supply of fuel and air, which is carried out by a number of sensors. They check the operating parameters, transmit them to the electronic unit, which analyzes and, based on them, corrects the operation of the entire system.
Moreover, sensors to provide complete information about the operation of the system are installed not only at the inlet (amount of fuel, air), but also in the exhaust system. It uses only one sensor, but how much air will be supplied to the cylinders depends on its operation. It is called an oxygen sensor, another name is a lambda probe.
Why do you need a lambda probe in a car?
1) metal case with thread and turnkey hexagon;
2) O-ring;
3) electric signal current collector;
4) ceramic insulator;
5) wires;
6) sealing wire collar;
7) current-carrying contact of the heater power wire;
8) external protective screen with an opening for atmospheric air;
9) sensitive element;
10) ceramic tip;
11) a protective screen with a hole for exhaust gases.
The main task of this oxygen sensor is to estimate the amount of unburned oxygen in the exhaust gases. The fact is that the most efficient combustion of the air-fuel mixture is achieved with a certain ratio of fuel and air - one part of gasoline must be mixed with 14.7 parts of air.
If the air-fuel mixture is lean, then the air content will be increased, and vice versa - a rich mixture will provide a lower percentage of oxygen in the exhaust gases. And this already affects the power, consumption, throttle response.
And since the engine operates in different modes, therefore, this ratio is far from always observed. In order to be able to control the amount of air supplied, a lambda probe is included in the power system.
Based on the readings of this sensor, the electronic unit evaluates the quality of the air-fuel mixture and, if it detects a non-compliance with the standards, corrects the operation of the system, ensuring that the optimal mixture is supplied by sending a signal to the injectors, which increase or decrease the amount of injected fuel.
The device and principle of operation of the lambda probe
The principle of operation of the lambda probe
The principle seems to be simple, but its implementation is not so easy. This sensor must compare the results with something in order to “understand” that a change in the percentage of oxygen has occurred. Therefore, he makes measurements in two places - atmospheric air and the one that remains after the combustion of the mixture. This allows him to "feel" the difference when changing the ratio of the air-fuel mixture.
1 – solid electrolyte ZrO2; 2, 3 - outer and inner electrodes; 4 - ground contact; 5 - "signal contact"; 6 - exhaust pipe
In this case, an electrical signal must be supplied to the electronic unit. To do this, the lambda probe needs to convert the measurement results into an impulse that will be applied to. To measure the concentration of oxygen in the atmosphere and in exhaust gases, two electrodes are used that react with it. That is, the principle of a galvanic cell is involved in the operation of this sensor, in which a change in the parameters of a chemical reaction entails a change in the voltage between the sensor electrodes. So, with an enriched mixture, when the percentage of oxygen is less, the voltage increases, and when it is depleted, it decreases.
The electrical impulse received as a result of a chemical reaction is fed to the computer, the parameters of which it compares with those registered in its memory and, as a result, it adjusts the operation of the power system.
Using chemical reactions to work, the lambda probe is not complex in design. Its main element is a ceramic tip made of zirconium dioxide (less often titanium dioxide) with a platinum coating, which acts as the electrodes that react. One side of the tip is in contact with the atmosphere, and the other side is in contact with the exhaust gases.
Heated lambda probe
The peculiarity of the work of such a ceramic tip is that the product of effective measurements of the residual percentage of oxygen is performed only under a certain temperature regime. In order for the tip to acquire the necessary conductivity, a temperature of 300-400 degrees is required. WITH.
To ensure the required temperature conditions, this sensor was initially installed closer to the exhaust manifold, which ensured that the required temperature was reached as the power plant warmed up. That is, he did not immediately enter the work. Before the lambda probe began to transmit impulses, the electronic unit was based on the readings of other sensors included in the power system, but optimal mixture formation was not observed.
Video: How to connect a heated lambda probe
Something else useful for you:
Some models of lambda probes have special electric heaters in their design, which provides faster access to the required temperature. The heater is powered from the car's on-board network.
The sensor, which performs its work due to a chemical reaction, is called a two-point sensor, due to the fact that measurements are made in two places. But another type of lambda probe is also produced - broadband, which is a more modern version of the sensor. Its design also uses a two-point element, as well as another ceramic element - pumping. In this case, the essence is reduced to the same supply of an electrical signal to the computer.
Using two or more sensors
Now many cars, in order to increase their environmental friendliness, use, which reduces harmful emissions into the atmosphere. In this case, the exhaust system is equipped with not one, but two or more oxygen sensors.
In such an exhaust system, these sensors not only measure residual oxygen, but also evaluate the efficiency of the converter. One of the sensors is installed in front of the catalyst, and the second - behind it. This allows, based on a comparison of the readings of two lambda probes, to understand whether the neutralization of harmful substances is being carried out.
On the one hand, such a system allows less pollution of the environment, but on the other hand, it is very “capricious”. One or two fillings with low-quality gasoline can easily ruin the converter. And this will already affect the readings of oxygen sensors, and as a result, the operation of the entire power supply system.
In addition, even if all the operating conditions of the car are observed, the converter will fail, because it has its own resource, after which it must be replaced in order to restore the normal operation of the power system. And since replacement is an expensive "pleasure", various tricks come to the rescue.
Many are simple, and in its place they install a flame arrester - an ordinary piece of pipe of the required diameter. And in order to get the difference in the readings of the two sensors, they use the so-called snag on the lambda probe - a special spacer that is installed on the second lambda probe.
This snag simply removes the tip from the exhaust flow, which affects its readings. Due to this, a difference is achieved, which the ECU perceives as the work of a catalyst.
Video: Lambda probe (oxygen sensor). How to fool the second lambda probe
Symptoms of an Oxygen Sensor Failure
A lambda probe is a fairly important element in a car's power system, and its breakdown can significantly affect the operation of the power plant. Its symptoms are as follows:
- increase in gasoline consumption;
- "floating" idle speed;
- decrease in acceleration dynamics;
- clicks and crackling from under the car after the engine stops;
One of the features of the lambda probe lies in the fact that its malfunction is far from always recognized by the auto self-diagnosis system. In addition, it is impossible to check it with conventional measuring instruments in garage conditions. Its performance is checked only by an oscilloscope.
It is also not repairable. The only thing that can be eliminated is a break in the wiring leading to the sensor. But with it there are also such malfunctions as damage to the heating element and loss of sensitivity of the sensor itself.
Video: How to check a lambda probe
Replacement
Therefore, many motorists do not try to diagnose the performance of lambda probes, but simply periodically replace it with a new one. To keep the power system in working order, it should be replaced every 2-3 years.
This operation is not complicated and it is performed on a viewing hole. You must first purchase the required sensor model. Before dismantling, the block of wires is disconnected from the probe, and then it is unscrewed from its seat with an open-end wrench of the appropriate size. To facilitate unscrewing, processing with special tools (WD-40 or others) is allowed. A new element is screwed in place of the unscrewed element and wiring is connected to it.
Models of lambda probes are special samples of the oxygen sensor, which is necessary for the correct operation of the electronic system in the combustion chambers. Thanks to this element, the system manages to balance and constantly control the percentage ratio between oxygen and gasoline. With the help of a probe, the electronic system constantly corrects the structure of the fuel mixture supplied to the engine, and also warns of destabilization in the engine's working process.
When this fragile device is used in very aggressive environments, it gradually wears out and requires replacement after only two years of use. By replacing the lambda probe, you can avoid engine damage. With a periodic check of the lambda probe, you will have a real guarantor of the stable operation of your car.
How does a lambda probe work?
The main purpose of the sensor is to timely determine the chemical composition of the exhaust gas and determine the level of oxygen percentage in it. In order to avoid problems in the operation of the engine, this indicator must be kept in the range of 0.1-0.3%.
Types of lambda probes
Now in the automotive equipment market, more and more often you can find only 2 variations of the device:
- The probe is based on a two-channel layout type. This type of sensor was mainly used in cars of the 80s, and is also used on modern economy class cars.
- Broadband lambda sensor. This type of probe is used as standard in 70% of medium and high class machines. This type of sensor not only accurately determines any deviations from the norm between the elements, but also promptly reports this to the system for instant position stabilization.
All samples of modern lambda probes are mounted in a special exhaust manifold, where the hoses and pipes are directly connected. This location of the sensor allows you to get the maximum performance and accuracy of this device.
The main task of any lambda probe is to significantly increase the working resources of the car by reducing fuel consumption and increasing stability in maintaining speed during idling. As a result, this sensor does not give specific values for the parameters of the fuel mixture, but reacts only when the values obtained are destabilized. After detecting a discrepancy with the specified parameters, the sensor transmits information to the central unit, which corrects the ratio of fuel to air.
Advice: if you have replaced the fuel filter on the Priore or another car, be sure to check the correct operation of the probe. If this part is replaced, the correct operation of the instrument may be impaired.
The main symptoms of a malfunction of the lambda probe
Among the signs that allow you to determine in advance whether the probe is working or not, the following are distinguished:
- The appearance of instability during engine operation (the engine starts to pick up speed sharply and also stalls sharply);
- Deterioration in the quality of the fuel mixture pumped by air into the cylinder system (this leads to excessive fuel consumption);
- Uncontrolled and inefficient fuel supply (malfunctions in the operation of the engine and the electronic system of the machine);
- The gradual appearance of intermittency in the engine at idle;
- Decreased efficiency of the engine at maximum speed;
- Problems in the operation of electronic systems (malfunctions in the sensor lead to unstable operation of the engine compartments, since the malfunction signal is transmitted with a delay);
- The presence of periodic "twitching" of the car;
- The appearance of incomprehensible pops during the operation of the engine;
- Untimely (slow) response of car engine systems to pressing the accelerator pedal;
- The appearance of a constantly flashing light about a sensor malfunction on the central instrument panel.
If you have found one or more of these causes in your vehicle, you should consider replacing this device.
Advice: one of the main indicators that the lambda probe is completely out of order is a constant sharp drop in engine power when revving.
Repair or replace the lambda probe?
As well as replacing the fuel pump with a VAZ-2110, so the repair of the lambda sensor should be carried out in a car service. However, in most cases, this spare part is completely replaced, as it simply cannot be further repaired. The problem is the high cost of original sensors from an authorized dealer.
As a result, most motorists decide to switch to using a universal sensor that fits almost any brand of car and costs much less than their native counterparts. In addition, if you want to save money, you can purchase a lambda probe from a showdown. There are used sensors, but they may have a long warranty period. You can also immediately purchase a full-fledged model of the exhaust manifold, in which a lambda probe is already installed.
If the problem is only in the presence of a small error during the operation of the sensor, you can quickly fix it yourself. The main symptoms of a malfunction are associated with its severe pollution during the sedimentation of the combustion products of the fuel. In order to understand whether the tightening of the cylinder head bolts affected the operation of the probe or not, it is enough just to show it to the specialists in the auto center. After the experts confirm the fact that the lambda probe you removed is working, you just have to carefully clean it from dust and burning sediment, and then put it back.
Do-it-yourself lambda sensor repair steps
To dismantle the lambda probe, it will be necessary to first warm up its surface to a limit of 60 degrees. Then carefully remove it and additionally take out the protective cap. After that, you can start cleaning with phosphoric acid, which helps to easily cope with any (even the most persistent) combustible deposits.
Advice: at the end of the work, before installation, do not forget to pre-lubricate the threads with a special sealant to ensure complete tightness of the product.
Video: how to check a lambda probe?
Most cars manufactured since the late 70s and early 80s are equipped with exhaust gas catalytic converters (colloquially -), which can significantly reduce the toxicity of waste materials, reducing the damage to the environment. A rather interesting fact is that the catalyst can retain its functionality only under conditions of ideal mixture formation, in which 1 part of the fuel accounts for 14.6 to 14.8 parts of atmospheric air with a normal oxygen content. To prevent the mixture from being over-enriched or over-depleted, it is necessary to use electronic control of the fuel supply - in such a system, the quality of the combustible composition is controlled by a lambda probe. Despite its location in an aggressive environment, this device is quite fragile and unstable, and is subject to frequent. If the lambda probe has stopped working in your car, signs of a malfunction can be detected without specialized equipment - it is impossible to continue operating the vehicle.
Mechanism of action
The lambda probe determines the chemical composition by searching for oxygen in them and determining the percentage. In the normal state of the mixture, this figure is 0.1–0.3% - small fluctuations are allowed due to the fact that the fuel supply to the engine cannot be stable for a significant period of time. The lambda probe is installed directly into the exhaust manifold - usually its installation is carried out at the junction of pipes extending from various cylinders (colloquially - "pants"), although there are other options.
There are various modifications of lambda probes - as well as vehicles of previous years of production, the devices have a two-channel layout. They can only determine the presence of a deviation in the oxygen content in a positive or negative direction, which is accompanied by a change in the voltage of the electrical signal transmitted to the electronic unit. However, all modern cars of the middle and elite classes are already equipped with broadband type lambda probes, which are already designed to determine the percentage deviation of the content of the desired element from the norm. Thanks to this, a significant improvement in the performance of the motor is achieved:
- Increases the stability of holding speed;
- Reduced fuel costs;
- The resource of the vehicle increases.
If you are interested in the electrical side of the lambda probe, then it is worth mentioning that this device cannot generate a uniform signal. Due to the fact that the standard lambda probe is located in the exhaust manifold, when the exhaust gases reach the point of its location, several work cycles may already have passed. At the same time, the quality of mixture formation deteriorates by 3–5%, which is accompanied by some destabilization of the engine. The lambda probe reacts to this by changing the voltage supplied to the central injection control unit, which takes the necessary measures.
We determine the breakdown
External signs
In the event of a malfunction of the lambda probe, a significant deterioration in the quality of the fuel mixture occurs, which is outwardly expressed in a deterioration in the operation of the engine. It is worth saying that there can be many - among them are the following main ones:
- Depressurization of the sensor housing, penetration of atmospheric air and exhaust gases into the interior;
- Overheating of the lambda probe as a result of inept tuning of the motor;
- Failure as a result of prolonged exposure to an aggressive environment (aging);
- Blocking of the working surface of the lambda probe by the products of combustion of low-quality fuel;
- Violations of the normal power supply and interruption of the line leading to the control unit;
- A strong blow to the body of the lambda probe with the destruction of internal components, for example, when actively driving on bad roads.
In all cases, except for mechanical damage accompanied by depressurization, malfunctions of the lambda probe appear gradually, with stepwise deterioration. Another exception is a broken wiring - however, it cannot be considered a malfunction of the lambda probe itself, so it should be considered in a separate topic for discussion. For all others, the following stages of development of faults can be distinguished.
Video on how to check a lambda probe:
At first, the device ceases to perform its functions normally in the limiting modes of engine operation, when its electrical characteristics are already deteriorating so much that the sensor cannot form. A malfunction of the lambda probe is manifested in the destabilization of the idle speed, which begin to “float” in a fairly wide range, the length of which is 300–600 rpm. When reaching very high speeds that do not belong to a critical level, a sharp change in the quality of the fuel mixture may occur. In this case, the car can twitch strongly, jerky pops can be heard from under the hood in some cases, and a warning lamp flashes on the engine, signaling abnormal engine operation. With a decrease in speed, all signs of a breakdown of the lambda probe disappear, but they cannot be ignored.
At the second stage, the device stops working on a cold engine - until the temperature reaches the maximum possible, the car will show all signs of a malfunction in the intake system or gas distribution mechanism. In particular, you will notice a significant reduction in power, extremely slow reactions to changes in the position of the gas pedal, as well as jerks and pops. In the event of a malfunction of the lambda probe, the car may twitch, slow down sharply as a result of a complete stop in the fuel supply, and. After about 5-10 minutes of driving in this unpleasant mode, there is a visible stabilization of the condition of the vehicle - however, this is only temporary.
If you do not take any measures regarding malfunctions of the lambda probe at the previous stage, the device will finally fail, which will cause many negative consequences. In addition to a significant deterioration in dynamics and the impossibility of normal movement in continuous mode, you will encounter an increase in fuel consumption by 15–30%, as well as a significant increase in exhaust toxicity, which can be determined by a clearly perceptible shade of fuel. Modern cars can generally block all driver actions with a faulty lambda probe by switching to emergency mode.
Worst case
If the lambda probe depressurization mentioned above has occurred, it is impossible to continue operating the car, as this can become a prerequisite for a complete failure of the engine, followed by expensive repairs. In this phenomenon, the exhaust gases enter a duct that is used to take atmospheric reference air in order to compare the two gases and determine the optimal oxygen content. If engine braking occurs, atmospheric air passes through with a minimum amount of impurities - therefore, the lambda probe sees that there is much more oxygen in the oxygen collector than in the environment! The result of this is the formation of powerful negative signals that completely disrupt the normal operation of the injection control unit.
Electronic diagnostics
If you want to know what signs of a malfunctioning lambda probe can be found during a professional inspection, you should find specialized equipment. When examining a lambda probe, an electronic oscilloscope is used - some experts recommend using a multimeter, but it can only state the fact that the device has failed. The device is checked on a running engine, heated to a circuit temperature of 80–90 degrees. In a cold state, the sensor may give readings that deviate significantly from the norm.
There can be many signs of a malfunctioning device. They are represented by flat signal characteristics or a level increase that does not exceed 0.1 V. In addition, you should pay attention to the shape of the curve - the changes should be steep enough to prevent a smooth increase in voltage. Experts say that the lambda probe must change the signal level every 120 ms - otherwise it is possible to talk about its malfunction.
Car repair
Almost all manufacturers of vehicles and individual components for them claim that the lambda probe cannot be repaired - only a complete replacement of the assembly is required. At the same time, its cost can be quite impressive - especially if you are the owner of a luxury brand car. A common way out is to purchase a universal sensor equipped with a special adapter for a specific type of vehicle. Such devices are manufactured by Bosch - using their services, you can even purchase used remanufactured parts, which are distinguished by a reduced cost and a limited duration. In addition, you can buy a used exhaust manifold with a pre-installed lambda probe.
If you are absolutely sure that the lambda probe is not functioning properly as a result of the deposition of combustion products on it, you can try it. To do this, the device is dismantled at a surface temperature of 40–50 degrees, the protective cap is removed from it, and the contacts are immersed in phosphoric acid. After several washes, the lambda probe is washed with clean water, dried thoroughly and put in place, not forgetting to lubricate the threads with a special sealing paste. The tightening torque is set by the manufacturer - it usually varies between 40–60 Nm. A similar procedure helps in 80% of the cases of the described malfunctions.
The main thing is timely diagnosis
If you find out in time that the malfunction of the car consists precisely in the breakdown of the standard lambda probe, you will be able to carry out the necessary repairs even before the consequences affect the engine, leading to its significant damage. In addition, by eliminating such a problem, you can keep the most important characteristics of the vehicle at the same level, which will help you to use it to the fullest and profitably. It is up to you to decide which troubleshooting method to choose, but it is worth remembering that working with car electronics without the appropriate qualifications is very dangerous.
