1. How does the oxygen sensor
2. Lifetime lambda probe
3. Because of what lambda probe fails
4. Symptoms of lambda probe malfunction
5. How to check lambda probe

How does the oxygen sensor

Lifetime lambda probe

Because of what lambda probe fails

Symptoms of lambda probe malfunction

How to check lambda probe

The purpose of the lambda probe (oxygen sensor) is to transfer information about the composition of the working mixture from the exhaust manifold to the ECU. The quality of the combustion of the fuel-air mixture (FA) directly affects the operation of the engine.

Proper operation of the oxygen sensor helps:

• Increase engine performance due to the definition of a near-ideal proportion of injected fuel and air.
• Reduce the production of harmful gases (CO, CH, NOx) emitted into the atmosphere and improve the economical operation of the car due to the correct composition of the working mixture.

On modern cars with an injection engine put one or more catalysts and two or more oxygen sensors. Where is the lambda probe? Depends on the type of car. Distributed system with two devices that are located before and after the catalyst. Thus, an excess of oxygen in the mixture is determined before the gases enter the device. In cars with one probe - installed in front, on the exhaust manifold.

How does the oxygen sensor

The computer measures the amount of fuel supplied by means of injectors, setting the volume at a certain point. The probe provides feedback that allows you to accurately determine the proportions of gasoline, diesel or gas. The computer requests information once every 0.5 seconds at idle. At higher speeds, the frequency of requests increases proportionally. Analyzing the data, the control unit adjusts the composition of the fuel assembly, making it poorer or richer. Maintaining optimum fuel assembly is the purpose of lambda probes. The ideal ratio of air and fuel is the proportions of 14.7: 1 (gasoline), 15.5: 1 (gas) and 14.6: 1 (diesel).

Types of oxygen sensors on the device design and principle of operation:

• Two-point, narrowband (simple). Works based on measuring the amount of oxygen in the exhaust gases. The poorer the fuel assembly, the lower the voltage, the richer the higher.
• Broadband. Generates a signal of a wider range for accurate assessment of the proportion in the fuel assembly.

Lifetime lambda probe

The average lifespan of oxygen sensors on Russian gasoline is 40,000–100,000 km. To increase the service life it is recommended to pour high-quality fuel with a low content of impurities and heavy metals. Self-diagnostics to determine the fault is quite difficult, to establish the cause - almost impossible. This may be wear, poor quality gasoline, mechanical damage and other factors.

If you suspect an oxygen sensor malfunction, consult a professional diagnostician. Using an oscillogram, the specialist will determine the cause of the malfunction and suggest ways to eliminate it.

Because of what lambda probe fails

• Mechanical damage. A severe blow as a result of an accident, hitting a curb or driving off-road adversely affects the state of the probe;
• Incorrect engine operation and failure of the ignition system lead to overheating of the oxygen sensor and breakage;
• Clogged system. The main cause of the failure of the lambda probe will be the products of combustion of poor-quality fuel. The more heavy metals, the faster it will become clogged;
• Breakdown in the piston group. A faulty piston, piston pin and connecting rod allow oil to flow into the exhaust system, which clogs the probe;
• Fluid ingress. Contamination of any kind will shorten the life of the probe;
• A wiring closure;
• Too rich or poor fuel / air mixture;
• The depressurization of the exhaust system permits air and exhaust gases, which disables the lambda probe;
• Misfire;
• Additives and "improvers" of fuel;
• Natural wear. In conditions of poor-quality fuel, the average sensor lifetime is 40–70 thousand km.

The failure of the lambda probe occurs gradually. The consequences of a faulty oxygen sensor are poured into engine emergency mode. So manufacturers save the car from serious damage, and the driver from emergencies.

The malfunction of the lambda probe is prevented by regular prophylaxis and diagnostics that detect breakdowns in the initial stages. If the oxygen sensor is out of order, read about ways to turn it off .

Symptoms of lambda probe malfunction

• The level of toxicity of gases increases. To determine the toxicity can be using diagnostics. Outwardly, not diagnosed, even the smell of the exhaust will not change.
• Increases fuel consumption. Each motorist monitors the fullness of the tank, trying to find their cruising speed when the flow is minimal. Therefore, increased fuel consumption will be noticed immediately. Depending on the severity of the lambda probe failure, it grows by 1–4 liters. Increased consumption, of course, can cause not only a faulty oxygen sensor.
• Oxygen sensor errors are issued (P0131, P0135, P0141 and others), “Check Engine” lights up. Usually, a check appears when a probe or catalyst malfunctions. Diagnostics will determine the exact cause.
• Catalyst overheats. Faulty lambda probes give the wrong signals to the ECU, which can lead to incorrect operation of the catalyst, its overheating up to the hot state, and subsequent failure.
• There is jerking and uncharacteristic popping in the engine. Lambda probes cease to generate the correct signal, which is why destabilized operation of the idling speed. Revolutions vary over a wide range, which leads to a deterioration in the quality of the fuel mixture.
• The dynamic characteristics of the car deteriorate, power is lost, and traction is lost. Similar signs appear in the started situations. Defective sensors also stop working on a cold engine, and the car signals the system in various ways.

If you are worried about one of these symptoms, consult a specialist. With the help of diagnostic equipment, it will determine the exact area of ​​damage and help in correcting.

How to check lambda probe

So, the car rides in jerks, increased fuel consumption, “Check Engine” caught fire. Symptoms are not characteristic only of lambda breakage, therefore a complete system diagnostics is needed. But if you are sure that the matter is in it, tell us how to check the sensor with your own hands.

Check oxygen sensors are recommended through the measurement of voltage values. A similar test of a lambda probe with a multimeter, a tester and an ohmmeter can be turned in your own garage.

The procedure is as follows:

1. Warm up the engine to operating temperature. A cold lambda probe will not work.
2. Remove and inspect the probe and wiring for mechanical damage and contamination. If it is bent, scratched or covered with soot build-up, lead bloom, white or gray soot, change it.
3. Check the operation of the lambda probe with an ohmmeter. Often the cause of the fault lies in the failure of the heating coil or the wires to it. How to call him? Connect an ohmmeter between the heater wires that were previously disconnected from the pad. With proper operation, the resistance of the signal circuit on different cars varies from 2 to 10 ohms and from 1 com to 10 mΩ in the heating circuit. If it is not at all, in the wiring break.
4. Test the probe signal with a motor tester, a switch voltmeter or an oscilloscope. Connect the tester between the ground wire and the signal, raise the speed to 3,000 Nm, note the time and watch the readings. They should vary from 0.1 to 0.9 volts. We recommend replacing the sensor if the range of changes in less than or 10 seconds has changed to less than 9-10 readings. The cause of the error may be in the "fatigue" and the slow response of the system.
5. Check the condition of the lambda probe through the reference voltage. Start the car, measure the voltage between ground and the signal wire. If the values ​​differ from 0.45 volts by more than 0.2, the sensor or circuits in the circuit leading to it are faulty.

If there are no devices to check the performance of the lambda probe, contact an expert. They will conduct a full diagnosis and accurately call the cause of the malfunction for less money and time that you would have spent on the purchase of devices and the identification of the malfunction yourself.

Video instruction:

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