Oxygen sensor Opel Astra

In the electronic engine management (ECM) system, the lambda probe is responsible for monitoring the oxygen concentration in the exhaust gases. The sensor data received by the ECU is used to regulate the fuel mixture supply to the combustion chambers of the cylinders.

The enrichment or lean indicators allow you to set the optimal proportions of fuel and oxygen for complete combustion and efficient operation of the unit. In the Opel Astra exhaust system, the oxygen sensor is located directly on the catalytic converter.

The device and principle of operation of the lambda probe

The lambda probe of the modern Opel Astra of the latest generation belongs to the broadband type with a galvanic cell based on zirconium dioxide. The design of the lambda probe consists of:

• Body.
• The first outer electrode is in contact with the exhaust gases.
• The inner electrode is in contact with the atmosphere.
• Solid type galvanic cell (zirconium dioxide) located between two electrodes inside the box.
• Heating the thread to create a working temperature (about 320°C).
• Spike on the casing for the intake of exhaust gases.

The operating cycle of the lambda probe is based on the potential difference between the electrodes, which are coated with a special oxygen-sensitive layer (platinum). The electrolyte heats up during the passage of a mixture of atmospheric air with oxygen ions and exhaust gases, as a result of which voltages with different potentials appear on the electrodes. The higher the oxygen concentration, the lower the voltage. The amplitude electrical impulse enters the ECU through the control unit, where the program estimates the degree of saturation of the exhaust system with oxygen based on the voltage values.

Diagnostics and replacement of the oxygen sensor

Failure of "oxygen" leads to problems with the engine:

• Increases the concentration of harmful emissions in exhaust gases
• RPMs drop to idle
• There is an increase in fuel consumption
• Decreased vehicle acceleration

The service life of a lambda probe on an Opel Astra averages 60-80 thousand km. Diagnosing a problem with an oxygen sensor is quite difficult - the device does not fail immediately, but gradually, giving the ECU incorrect values ​​\uXNUMXb\uXNUMXband failures. The causes of premature wear may be low-quality fuel, engine operation with worn elements of the cylinder-piston group, or improper valve adjustment.

An oxygen sensor failure is recorded in the ODB memory log, error codes are generated, and the "Check Engine" light on the instrument panel lights up. Decryption of error codes:

• P0133 - Voltage readings are too high or too low.
• P1133 - Slow response or sensor failure.

Sensor malfunctions can be caused by short circuits, broken wires, oxidation of the terminal contacts, vacuum failure (air leakage in the intake lines) and malfunctioning injectors.

You can independently check the performance of the sensor using an oscilloscope and a voltmeter. To check, measure the voltage between the impulse wire (+) - on the Opel Astra h black wire and ground - white wire. If on the oscilloscope screen the signal amplitude per second varies from 0,1 to 0,9 V, then the lambda probe is working.

It must be remembered that the oxygen sensor is checked with the engine warmed up to operating temperature at idle.

Replacement procedure

To replace the oxygen sensor with an Opel Astra h, a key other than 22 is required. Before work, it is necessary to remove the “negative” terminal of the battery and allow the elements of the exhaust system to cool.

• Press the clamp of the harness block to the terminals of the lambda probe.

• Disconnect wiring harnesses from engine.

• Remove the catalytic converter heat shield cover on the manifold.

• Unscrew the nut securing the lambda probe with a key to “22”.

• Unscrew the oxygen sensor from the manifold mount.

• A new lambda probe is installed in the reverse order.

When replacing, all work must be carried out on a cooled engine at a temperature not higher than 40-50 ° C. The threaded connections of the new sensor are treated with a special thermal sealant that can withstand high temperatures to prevent "sticking" and prevent moisture from entering. O-rings are also replaced with new ones (usually included in the new kit).

The wiring should be checked for insulation damage, breaks and oxidation on the contact terminals, which, if necessary, are cleaned with fine-grained sandpaper. After installation, the operation of the lambda probe is diagnosed in different engine operating modes: 5-10 minutes at low idle, then an increase in speed to a maximum of 1-2 minutes.