Oxygen Sensor

TEST PROCEDURE
Status Monitoring
The prerequisite for carrying out this test is that the oxygen sensor must be at operating temperature. The indicated voltage signal is picked off in steps and fluctuates between 0.02 and 0.85 V.

When the oxygen sensor is not in operation, or a wire to the DME control unit has a break, a constant value of 0.45 V is indicated.

An oxygen sensor may be defective (e.g. due to deposits) and still indicate the required voltage signals. An indication for such a case may be when CO-measured values deviate from the nominal value despite the emission control system being active.

Test option
Disconnect the Digital Motor Electronic (DME) control unit from the voltage supply for at least 5 minutes. Then disconnect the oxygen sensor, start the engine and perform CO measurement once again. If the CO value approaches the nominal value, the oxygen sensor should be replaced and CO measurement repeated.