You probably know that your car has an oxygen sensor (or even two!) ... But why is it needed and how does it work? FAQs are answered by Stefan Verhoef, DENSO Product Manager (Oxygen Sensors).

Q: What is the job of an oxygen sensor in a car?
O: Oxygen sensors (also called lambda probes) help you monitor your vehicle's fuel consumption, which helps reduce harmful emissions. The sensor continuously measures the amount of unburned oxygen in the exhaust gases and transmits this data to the electronic control unit (ECU). Based on this information, the ECU adjusts the fuel-to-air ratio of the air-fuel mixture entering the engine, which helps the catalytic converter (catalyst) work more efficiently and reduce the amount of harmful particles in the exhaust gases.

Q: Where is the oxygen sensor located?
O: Every new car and most cars made after 1980 are equipped with an oxygen sensor. Typically, the sensor is installed in the exhaust pipe before the catalytic converter. The exact location of the oxygen sensor depends on the type of engine (V or in-line) and the make and model of the vehicle. To determine where the oxygen sensor is located in your vehicle, refer to the owner's manual.

Q: Why does the air-fuel mixture need to be constantly adjusted?
O: The air-fuel ratio is critical because it affects the efficiency of the catalytic converter, which reduces carbon monoxide (CO), unburned hydrocarbons (CH) and nitrogen oxide (NOx) in the exhaust gases. For its effective operation, a certain amount of oxygen in the exhaust gases is necessary. The oxygen sensor helps the ECU determine the exact air-fuel ratio of the mixture entering the engine by providing the ECU with a rapidly changing voltage signal that changes according to the oxygen content in the mixture: either too high (lean) or too low (rich). The ECU reacts to the signal and changes the composition of the air-fuel mixture entering the engine. When the mixture is too rich, fuel injection is reduced. When the mixture is too lean, it increases. The optimal air-fuel ratio ensures complete combustion of the fuel and uses almost all of the oxygen in the air. The remaining oxygen enters into a chemical reaction with toxic gases, as a result of which harmless gases exit the neutralizer.

Q: Why do some cars have two oxygen sensors?
O: Many modern cars, in addition to the oxygen sensor located in front of the catalyst, are also equipped with a second sensor installed after it. The first sensor is the main one and helps the electronic control unit regulate the composition of the air-fuel mixture. The second sensor, installed after the catalyst, monitors the efficiency of the catalyst by measuring the oxygen content in the exhaust gases at the outlet. If all the oxygen is taken up by the chemical reaction between the oxygen and the pollutants, then the sensor generates a high voltage signal. This means that the catalyst is working properly. As the catalytic converter wears out, some of the harmful gases and oxygen cease to participate in the reaction and leave it unchanged, which is reflected in the voltage signal. When the signals become the same, this will indicate a failure of the catalyst.

Q: What are the sensors?
ABOUT: There are three main types of lambda sensors: zirconia sensors, air-fuel ratio sensors, and titanium sensors. All of them perform the same functions, but they use different ways of determining the ratio "air-fuel" and different outgoing signals for transmitting the measurement results.

The most widespread technology is based on the use zirconia sensors(both cylindrical and flat types). These sensors can only determine the relative value of the coefficient: above or below the fuel-air ratio of the lambda coefficient of 1.00 (ideal stoichiometric ratio). In response, the engine ECU gradually changes the amount of fuel injected until the sensor begins to indicate that the ratio has reversed. From this point on, the ECU again begins to correct the fuel supply in the other direction. This method allows you to slowly and continuously "float" around the lambda factor of 1.00, while not allowing you to maintain an exact factor of 1.00. As a result, under changing conditions, such as hard acceleration or braking, zirconium oxide sensor systems are under-fueled or over-fueled, resulting in reduced catalytic converter efficiency.

Air-fuel ratio sensor shows the exact ratio of fuel and air in the mixture. This means that the engine ECU knows exactly how much this ratio differs from the lambda 1.00 ratio and, accordingly, how much the fuel supply needs to be adjusted, which allows the ECU to change the amount of fuel injected and obtain a lambda ratio of 1.00 almost instantly.

Air-fuel ratio sensors (cylindrical and flat) were first developed by DENSO to ensure vehicles meet stringent emission standards. These sensors are more sensitive and efficient than zirconia sensors. Air-fuel ratio sensors provide a linear electronic signal of the exact ratio of air and fuel in the mixture. Based on the value of the received signal, the ECU analyzes the deviation of the air-fuel ratio from stoichiometric (that is, Lambda 1) and corrects the fuel injection. This allows the ECU to accurately adjust the amount of injected fuel, instantly reaching and maintaining the stoichiometric ratio of air and fuel in the mixture. Systems using air-fuel ratio sensors minimize the possibility of insufficient or excess fuel supply, which leads to a reduction in harmful emissions into the atmosphere, lower fuel consumption, and better vehicle controllability.

Titanium sensors in many ways similar to zirconia sensors, but titanium sensors do not require atmospheric air to operate. Thus, titanium sensors are the optimal solution for vehicles that need to cross deep fords, such as four-wheel drive SUVs, since titanium sensors are able to work when immersed in water. Another difference between titanium sensors and others is the signal they transmit, which depends on the electrical resistance of the titanium element, and not on voltage or current. Given these features, titanium sensors can only be replaced by similar ones and other types of lambda probes cannot be used.

Q: What is the difference between special and universal sensors?
O: These sensors have different installation methods. Special sensors already have a connector in the kit and are ready for installation. Universal sensors may not be equipped with a connector, so you need to use the connector of the old sensor.

Q: What happens if the oxygen sensor fails?
O: If the oxygen sensor fails, the ECU will not receive a signal about the ratio of fuel and air in the mixture, so it will set the amount of fuel to be supplied arbitrarily. This can lead to less efficient use of fuel and, as a result, an increase in fuel consumption. This can also cause a decrease in catalyst efficiency and an increase in emissions toxicity.

Q: How often should the oxygen sensor be changed?
O: DENSO recommends that the sensor be replaced according to the vehicle manufacturer's instructions. However, the performance of the oxygen sensor should be checked every time the vehicle is serviced. For engines with a long service life or with signs of increased oil consumption, the intervals between sensor replacements should be shortened.

Range of oxygen sensors

412 part numbers cover 5394 applications, which corresponds to 68% of the European vehicle fleet.
Oxygen sensors with and without heating (switchable type), air-fuel ratio sensors (linear type), lean mixture sensors and titanium sensors; two types: universal and special.
Regulating sensors (installed before the catalyst) and diagnostic (installed after the catalyst).
Laser welding and multi-stage control ensure that all features are exactly matched to original equipment specifications, ensuring performance and long-term reliability.

DENSO solved the problem of fuel quality!

Are you aware that poor quality or contaminated fuel can shorten the life and degrade the performance of an oxygen sensor? Fuel can be contaminated with engine oil additives, gasoline additives, sealant on engine parts, and oil deposits after desulfurization. When heated above 700 °C, contaminated fuel emits vapors harmful to the sensor. They interfere with sensor performance by forming deposits or destroying sensor electrodes, which is a common cause of sensor failure. DENSO offers a solution to this problem: the ceramic element of DENSO sensors is coated with a unique protective layer of aluminum oxide, which protects the sensor from poor quality fuel, extending its life and maintaining its performance at the required level.

Additional Information

For more information on DENSO's range of oxygen sensors, see Oxygen Sensors, TecDoc, or contact your DENSO representative.

What is this service?

Lambda probe - oxygen sensor, installed in the exhaust manifold of the engine. Allows you to estimate the amount of remaining free oxygen in the exhaust gases. The signal from this sensor is used to regulate the amount of fuel supplied. To diagnose a malfunction of this element, it is best to use the "Computer diagnostics of all systems" service. You should not continue to operate a car with a faulty lambda probe, as this can lead to the failure of expensive elements, such as a catalytic converter.

The air-fuel ratio sensor is an integral part of the car engine power system, which allows you to realistically assess the amount of oxygen remaining in the exhaust gases, and thereby adjust the composition of the working mixture by the electronic control unit. When it malfunctions, it is necessary complete lambda sensor replacement.

The main function of the air fuel ratio sensor or lambda probe is to determine the air-fuel ratio in the exhaust gases and estimate the amount of free oxygen in the exhaust gases. Based on its data, the best exhaust gas cleaning, more precise control of the exhaust gas recirculation system and regulation of the amount of fuel injected at full engine load are provided. If it malfunctions, a complete replacement of the sensor is necessary, because it is it that allows you to adjust the composition of the working mixture and ensure the normal operation of the vehicle control system. It is not uncommon for an oxygen sensor to fail. You need to call the wizard, who will check if you need it.

Therefore, at the first signal of the indicator light, stop using the car and tow it to the service, check the condition of the vacuum hoses and the tightness of the exhaust system. It's a simple process that takes about half an hour. This does not require dismantling the engine and removing the protection of the oil pan, it is enough just to dismantle the wheel. So if a specialist comes, let

Keep in mind

A faulty air fuel ratio sensor can cause engine misfiring and mishandling, poor fuel economy and catalytic converter failure.

• maintain your vehicle in good condition and carry out regular maintenance;
• replacement of the lambda probe sensor is necessary at the first light of the indicator light;
• have the vehicle towed to a service center and check the condition of the air fuel ratio sensor.

The ideal ratio of gasoline and air , in which the entire mixture burns completely is considered stoichiometric (ideal). The engine works well if the gasoline + air mixture burns well. The mixture burns well if it is optimal. The mixture is optimal if 1 g of gasoline is supplied to 14.7 g of air. The optimal fuel-air mixture burns as quickly as possible and gives the right amount of energy without unnecessary heat. The main thing in the optimal formation of the fuel-air mixture is the DMRV.

AFR is the ratio of air to fuel in an engine's combustion chamber.

Ideal ratio fuel and air for gasoline engines(stoichiometric mixture) = 14.7/1 (AFR) for petrol/diesel.

14.7 g of air per 1 g of gasoline.

Each fuel needs its own fuel/air ratio.

Lean or rich mixture.The air-fuel mixture can be lean or rich.

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Poor mixture (injector), signs and consequences

Mixture setting

While driving Pilot see in real time which mixture is lean or rich.

Poor mixture signs- a stalling engine, more than 14.7 g of air, ignites faster and is accompanied by excessive heating .. Such a mixture is prone to detonation, at low speeds it is not scary. At full load, mixture 14 is already considered hazardous. Doing the whole system on a mixture of 14.7 is not reasonable. At low revs, this will not be enough for acceleration, and at higher revs, you will simply catch detonation.

Poor mixture consequences- at high speeds, with a full load, the level of detonation reaches catastrophic consequences. Piston burnt or fused, valves or spark plugs burnt out. Rising temperatures and loss of power are the simplest things that can happen to an engine when knocking. Usually it is a jammed and overheated motor.

On VAF "e, the consumption was about 25 liters in the city, and on a normally configured converter,15 l in the city, so consider the benefit. I thank smart, honest, temperamental for feedback and dissemination of information.

Rich mixture (injector), signs and effects

Mixture setting

richmix signs

• Fuel consumption has risen sharply.
• Exhaust gases are black or grey.
• Air is less than 14.7g, safer and more reliable for the engine.

A rich mixture of consequences - long-term operation of the engine on a rich mixture can lead to piston failure and failure of the spark plugs.

While driving Pilot records the operation of the oxygen sensor and the air flow sensor. At the same time, it is possible see in real time whether the mixture is lean or rich.

In the end, I want to thank the guys who are involved in this project, I hope their thing will serve me for a long time. By the way, this version is suitable for both mechanics and automatic transmission, I have an automatic transmission, so for me it is a gift of fate I would say! TPS Pilot contactless I thank smart, honest, temperamental for feedback and dissemination of information.

Reasons for the formation of a rich mixture of an injection engine

• injectors deliver too much fuel
• air filter clogging
• poor throttle performance
• fuel pressure regulator malfunction
• air flow sensor malfunction
• evaporative emission system malfunction
• incorrect operation of the economizer.

It works on cars that do not work on traditional methods such as spacers for lambda probes and circuits such as a capacitor + resistor. Electronic emulator Lambda probe Catalyst 2-channel Pilot .. For engines with two catalysts and two additional oxygen sensors - you need to buy one emulator. Support for lambda probes with offset signal ground. ElectI thank smart, honest, temperamental for feedback and dissemination of information.

lambda sensor

The readings of the lambda sensor are the ratio of the current mixture to the ideal one.

Example: current mixture - air 12.8 g. Lambda sensor readings 0.87=12.8 / 14.7

The ECU takes into account the readings of the lambda sensor only with uniform movement.

When accelerating, braking and warming up, the ECU does not take into account the readings of the lambda sensor and works according to the program.

When tuning, you need to catch the transition from a lean mixture to a rich one. From this point to do a little richer.

In this case, the lambda sensor jumps from 0 to 1. The transition point is approximately 0.45.

For other modes of engine operation, a broadband sensor is used.

The reached maximum speed - about 200-210 km / h did not measure the dynamics, but in the test run they somehow crossed with the E39 M50B20, well, they lit it - it turned out that he is not my rival in terms of dynamics neither from the bottom, nor at three-digit speeds. The actual consumption fluctuates around 11l of the 92nd. Replacing the flow meter with a non-native one without firmware! + mix setting Converter Pilot + BLUETOOTH I thank smart, honest, temperamental for feedback and dissemination of information.

Air is central to optimal education fuel-air mixture is DMRV

Accurate injection of gasoline is easier than precise injection of air. Errors in the calculation of the incoming air lead to problems in the operation of the engine. The errors will be smaller if the air flows in a uniform flow. Flow uniformity is created:

• smooth duct walls
• smooth turns of the air duct (1- 2)
• the absence of pulsations and swirls (remove everything that leads to this from the flow, especially the "nulevik" filter)

If everything is in order along the gasoline supply line, then the main thing in the optimal formation of the mixture is the DMRV (mass air flow sensor). Based on its signals, the ECU supplies gasoline. At the exit there is a "controller" (lambda probe) and "sniffs" the exhaust gases. It determines what is a lot - gasoline or air and informs the ECU. The ECU adjusts the fuel supply.

When you change the flow meter to a non-original one (VAF to MAF), then:

• constructively change the direction for the air flow - this is very important
• should solve the problem with the inlet air temperature sensor (if it is missing, it will not start in winter)
• and most importantly, put a "translator" for the ECU so that the ECU understands which signal of the old flow meter corresponds to the signal of the new flow meter (these are devices such as the Pilot VAF / MAF converter, MAF Emulator 3, "Winners Sensor" (Winners)).
• after all changes, the mixture needs to be adjusted.

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I read their local forum and came to the conclusion that this is a super-duper-mega-PANACEA! The advantage of this converter is its customization flexibility. He even supports ShPLZ! Converter Pilot + BLUETOOTH - mixture setting I thank smart, honest, temperamental for feedback and dissemination of information.

Inlet air temperature sensor

There are two ways to solve the problem of the intake air temperature sensor:

1. put a resistor instead of it and the ECU will think that you have summer +20 all year round
2. open the VAF and remove the sensor from it, and install it in the intake manifold (according to the results, this option is better)

Engine

The engine has several modes of operation:

• idle and warm up
  

neutral, gearbox not connected

idling with the box connected, standing at a traffic light

• uniform motion
• acceleration, braking - smooth
• acceleration (WOT), braking - sharp

Harsh acceleration, braking - this is a sharp effect on the air flow (throttle). We get ripples and swirls.

Sharp acceleration - a lot of air, but little gasoline. Add gasoline in an emergency - the accelerator pump should turn on.

Hard braking - little air, a lot of gasoline. Add air in an emergency - an additional air supply channel should open.

For both modes - the "retarder" of the throttle opening should work. The throttle valve assembly is equipped with a smooth gas release system - a purely mechanical damper system that slows down not abruptly, but smoothly when the accelerator pedal is released. It seems that it was precisely its adjustment that made it possible, at least now it has been verified that this is the case, to ensure a smooth decrease in engine speed without jittering.

Solving the problem with poor engine performance:

• check everything related to the supply of gasoline
• check everything related to the air supply

Action algorithm:

1. Count errors.
2. If item 1 is not fulfilled, then we logically determine which is more gasoline or air. Or the smell from the exhaust pipe. The color of the candles.
3. Determined - gasoline is low.
4. We go along the line of supply of gasoline:

• Mechanics(part wear, deformation, accelerator pump, gas pump, fuel filter, injectors, fuel pump mesh, gas tap, small passage hole inside the tap. Corrected: by replacing the tap or drilling.),
• electrician(contacts, wires, correct connection),
• time trigger(injector keys, ignition angle, distributor, candles),
• temperature triggered-worse for hot (some part heated up and the gap between it and the neighboring one decreased, friction appeared or the gap increased and there was no contact - the timing belt, the tension roller just dangled, the camshafts were out of sync with the crankshaft and the engine stalled. , bypass roller, spring, DTVV, DTOZH)

5. Air - not enough. I put the pilot, I'm quite satisfied, the machine is unrecognizable. Plus converter is the ability to adjust to changes with the engine. You can still diagnose the death of two sensors (DMRV and LZ), which is also necessary. All in all this item is worth the money, I have already seen in practice. Now it has become much more pleasant for me to ride without all sorts of poddergush and floating xx. The car goes as it was intended and it certainly pleases me! And, believe me, no more or less, and it works with a bang! Converter Pilot + BLUETOOTH - mixture setting I thank smart, honest, temperamental for feedback and dissemination of information.

Setting the air/fuel mixture (AFR)

The purpose of tuning is to get maximum power and maximum torque during hard acceleration, with moderate consumption in city and on the highway.

There are two ways to set up a mixture:

1. trimming resistor - a limited range ("Sensor Winners" (Winners)). Before that, be sure to set the basic settings through VAGCOM.
2. using software (MAF Emulator 3, Pilot VAF/MAF). The software from MAF Emulator 3 is configured for broadband lambda, and the software from the Pilot VAF / MAF converter is configured for conventional lambda.

Set up step by step:

1. XX setting,
2. further adjustment of overclocking.
3. The most correct is the uphill mode.
4. If you can tune the engine as efficiently as possible in this mode, then consider that the tuning was a success. Never set the entire rpm range in neutral.

The higher the speed, the richer the air-fuel mixture, and the earlier the ignition angle.

Don't forget before you start set the mechanical ignition timing according to the stroboscope.

Electronic emulator+ BLUETOOTH Lambda Probe Catalyst 2 Channel Pilot 1. There is a setting for emulation parameters
2. There is logging - recording of all emulation parameters while the car is moving
3. Engine type: any 4. Installation: open circuit
5. Programming: Yes
6. Diagnostics saved
7. Before being sent to the client, it undergoes a mandatory parameter setting and performance test.
8. Support Euro 3, 4, 5, 6
9. No intervention in the software part of the computer
10. Warranty - 1 year Elect ron blende Pilot + BLUETOOTH. I thank smart, honest, temperamental for feedback and dissemination of information.

In another way, it is also called an oxygen sensor. Because the sensor detects the oxygen content in the exhaust gases. By the amount of oxygen contained in the exhaust, the lambda probe determines the composition of the fuel mixture, sending a signal about this to the ECU (Electronic Control Unit) of the engine. The operation of the control unit in this cycle is that it issues commands to increase or decrease the duration of injection, depending on the readings of the oxygenator.

In another way, it is also called an oxygen sensor. Because the sensor detects the oxygen content in the exhaust gases. By the amount of oxygen contained in the exhaust, the lambda probe determines the composition of the fuel mixture, sending a signal about this to the ECU (Electronic Control Unit) of the engine. The operation of the control unit in this cycle is that it issues commands to increase or decrease the duration of injection, depending on the readings of the oxygenator.

The mixture is controlled so that its composition is as close as possible to stoichiometric (theoretically ideal). A mixture composition of 14.7 to 1 is considered stoichiometric. That is, 1 part of gasoline should be supplied to 14.7 parts of air. It is gasoline, because this ratio is valid only for unleaded gasoline.

For gas fuel, this ratio will be different (it seems to be 15.6 ~ 15.7).

It is believed that it is at this ratio of fuel and air that the mixture burns completely. And the more completely the mixture burns, the higher the engine power and the lower the fuel consumption.

Front oxygen sensor (lamda probe)

The front sensor is installed before the catalytic converter in the exhaust manifold. The sensor determines the oxygen content in the exhaust gases and sends data on the composition of the mixture to the ECU. The control unit regulates the operation of the injection system, increasing or decreasing the duration of fuel injection by changing the duration of the injector opening pulses.

The sensor contains a sensitive element with a porous ceramic tube, which is surrounded by exhaust gases from the outside, and atmospheric air from the inside.

The ceramic wall of the sensor is a solid electrolyte based on zirconium dioxide. The sensor has a built-in electric heater. The tube starts working only when its temperature reaches 350 degrees.

Oxygen sensors convert the difference in oxygen ion concentration inside and outside the tube into a voltage output signal.

The voltage level is due to the movement of oxygen ions inside the ceramic tube.

If the mixture is rich(more than 1 part of fuel is supplied to 14.7 parts of air), there are few oxygen ions in the exhaust gases. A large number of ions move from the inside of the tube to the outside (from the atmosphere to the exhaust pipe, so it's clearer). Zirconium during the movement of ions induces an EMF.

The voltage at a rich mixture will be high (about 800 mV).

If the mixture is lean(Fuel is less than 1 part), the difference in ion concentration is small, so a small amount of ions move from inside to outside. This means that the output voltage will also be small (less than 200 mV).

With a stoichiometric composition of the mixture, the signal voltage changes cyclically from rich to lean. Since the lambda probe is located at some distance from the intake system, such inertia of its work is observed.

This means that with a working sensor and a normal mixture, the sensor signal will vary from within the range from 100 to 900 mV.

Malfunctions of the oxygen sensor.

It happens that lambda makes mistakes in its work. This is possible, for example, when air is sucked into the exhaust manifold. The sensor will see a lean mixture (low fuel), although in fact it is normal. Accordingly, the control unit will give the command to enrich the mixture and add the duration of the injection. As a result, the engine will run on reenriched mixture, and constantly.

The paradox in this situation is that after a while the ECU will give an error "Oxygen sensor - mixture too lean"! Did you catch the scam? The sensor sees a lean mixture and enriches it. In reality, the mixture is, on the contrary, rich. As a result, the candles, when twisted, will be black from soot, which indicates a rich mixture.

Do not rush to change the oxygen sensor with such an error. You just need to find and eliminate the cause - air leakage into the exhaust tract.

The reverse error, when the ECU issues a fault code indicating a rich mixture, also does not always indicate this in reality. The sensor may simply be poisoned. This happens for various reasons. The sensor is “etched” by vapors of unburned fuel. With prolonged poor engine operation and incomplete combustion of fuel, the oxygenator can easily be poisoned. The same applies to very poor quality gasoline.

Increased emissions of harmful substances occur when the air-fuel ratio in the mixture is not adjusted correctly.

Fuel-air mixture and engine operation

The ideal ratio of fuel and air for gasoline engines is 14.7 kg of air per 1 kg of fuel. This ratio is also called the stoichiometric mixture. Virtually all gasoline engines are now powered by the combustion of such an ideal mixture. The oxygen sensor plays a decisive role in this.

Only at this ratio, complete combustion of the fuel is guaranteed, and the catalyst almost completely converts harmful exhaust gases hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx) into environmentally friendly gases.
The ratio of the actual air used to the theoretical demand is called the oxygen number and is denoted by the Greek letter lambda. For a stoichiometric mixture, lamba is equal to one.

How is this done in practice?

The composition of the mixture is controlled by the engine control system ("ECU" = "Engine Control Unit"). The ECU controls the fuel system, which supplies a precisely metered fuel-air mixture during the combustion process. However, for this, the engine management system needs to have information whether the engine is currently running on an enriched (lack of air, lambda less than one) or lean (excess air, lambda greater than one) mixture.
This crucial information is provided by the lambda probe:

Depending on the level of residual oxygen in the exhaust gas, it gives different signals. The engine management system analyzes these signals and regulates the supply of the fuel-air mixture.

Oxygen sensor technology is constantly evolving. Today, lambda control guarantees low emissions, efficient fuel consumption and long catalyst life. To achieve the operating state of the lambda probe as quickly as possible, a highly efficient ceramic heater is used today.

The ceramic elements themselves are getting better every year. This guarantees even more accurate
measurement and ensures compliance with more stringent emission standards. New types of oxygen sensors have been developed for special applications, such as lambda probes, the electrical resistance of which changes with the composition of the mixture (titanium sensors), or broadband oxygen sensors.

The principle of operation of the oxygen sensor (lambda probe)

In order for the catalyst to work optimally, the ratio of fuel and air must be very precisely matched.

This is the task of the lambda probe, which continuously measures the residual oxygen content in the exhaust gases. By means of an output signal, it regulates the engine management system, which thereby precisely sets the fuel-air mixture.