Test Point 15 - Oxygen Sensor Operation

TEST POINT 15

Oxygen Sensor Operation

Brief test
- Engine at operational temperature
- Idle speed correctly adjusted




1. Connect exhaust sampling line to test socket of catalytic converter

2. Connect emission testing device to exhaust sampling line.




3. Disconnect oxygen sensor connector and note CO-value.




4. Disconnect vacuum line from fuel pressure regulator and block line with a suitable plug.
Figure shows pressure regulator with engine removed.
The CO-value must increase.

5. Reconnect oxygen sensor connector. The CO-value must reset automatically to the specified value 0.6 ± 0.2%.
If the CO-value does not change, either the oxygen sensor or the DME control unit is defective.

DME Control Unit (Oxygen Control Function)

1. Same preconditions as for oxygen sensor operation test.

2. Use an extra lead to briefly connect terminal 1 of the oxygen sensor plug-in connector (control- unit half of plug) to ground.
The CO-value must increase.

If the CO value does not change, check the connection to the DME control unit (terminal 24) and replace control unit if necessary.

Testing Oxygen Sensor (Sensor Voltage)

1. Same preconditions as for test of oxygen sensor operation.

2. Disconnect oxygen sensor connector.

3. Connect voltmeter to ground and terminal 1 (oxygen-sensor half of connector).
The voltage must be between 0.1 V and 1.0 V.
(Sensor voltage depending on oxygen content in exhaust gas.)