General information
The oxygen sensor determines the concentration of oxygen in the exhaust gases and accordingly changes the voltage of the signal that enters the electronic engine control unit.
On models with 2.0L/2.4L engines, a zirconia oxygen sensor is installed (ZrO2), whose signal voltage is approximately 1 V, if the composition of the air-fuel mixture is richer than the stoichiometric ratio (those. if the oxygen concentration in the exhaust gases is low). If the air-fuel mixture is leaner than the stoichiometric ratio (those. if the concentration of oxygen in the exhaust gases is high), then the voltage of the sensor signal is approximately 0 V. Based on this signal, the electronic engine control unit regulates the fuel supply to the cylinders so that the composition of the air-fuel mixture is as close to the stoichiometric ratio as possible.
The oxygen sensor is equipped with a heater, which ensures stable operation of the sensor in all modes.
Troubleshooting Guide
1. If the oxygen sensor is defective, then the exhaust gases will contain an increased content of toxic substances.
2. If the oxygen sensor signal (output voltage) differs from the nominal value, after the test showed that the sensor is working, then the cause of the malfunction in the components of the air-fuel mixture control system:
- A) Injector failure;
- b) Air enters the intake manifold through a damaged gasket;
- V) Malfunction of the air flow sensor, intake manifold air temperature sensor, intake manifold absolute pressure sensor and coolant temperature sensor;
- G) Poor contact or incorrect connection of connectors.
Note:
- If the accelerator pedal is released abruptly while the engine is running at 4000 rpm, the fuel supply will be turned off for a short period of time and the tester will read the oxygen sensor signal voltage of 200 mV or less.
- If you sharply press the accelerator pedal, the air-fuel mixture will be enriched and the tester will show the oxygen sensor signal voltage of 600 - 1000 mV.
- If the engine is idling, then the oxygen sensor signal voltage will fluctuate between 400-600 mV. In this case, the oxygen sensor can be considered serviceable.
Sensor test
Note:
- Before checking, warm up the engine so that the coolant temperature reaches 80-95°C.
- When taking measurements, use an ultra-precise digital voltmeter.
1. Disconnect the oxygen sensor connector and measure the resistance between the terminals "3" And "4".
- Rated value (at 400°C): 30 kΩ or more
2. If there is a malfunction, replace the oxygen sensor.
3. Connect the power (battery voltage) straight to the conclusion "3" And "4" sensor.
Note: Be careful when performing this operation. Applying voltage to the outputs "1" And "2" will damage the oxygen sensor.
4. Connect a digital voltmeter with a high internal resistance between the leads "1" And "2".
5. While periodically depressing the accelerator pedal, measure the output voltage of the oxygen sensor. Rated value (when pressing the accelerator pedal):
- Oxygen sensor output voltage: 0.6 V minimum
- Resistance: 30 ohms or more
6. If the sensor signal is not correct, then the oxygen sensor may be defective and must be replaced.
Torque:
- Oxygen sensor: 40-50 Nm
- Oxygen sensor wiring retainer bolt: 8-12 Nm