Test Point 7 - Oxygen sensor
TEST POINT 7 - Oxygen sensor (V) - (Sensor signal) Fault code 1_22Possible Causes, Elimination, Remarks
Checking the sensor signal
Using the System Tester 9288, the oxygen sensor signal may be read directly under the Actual values menu item. Diagnosis can only be carried out if an engine temperature of 70°C has been reached for more than 1 minute.
If not: Disconnect oxygen sensor plug.
Connect digital voltmeter with terminals 3 and 4 at the sensor end.
Start engine and allow to warm up so that the oxygen sensor reaches its operating temperature. When the mixture is enriched, e.g. during acceleration, a change in the voltage signal must be displayed.
Display: approx. 150 mV - 900 mV (acc. to mixture composition) Oxygen sensor heating test
In case of delayed regulation response, check the oxygen sensor heating. To do so, connect voltmeter to terminals 1 (+) and 2 of the disconnected sensor plug on the control unit end with the engine running. On-board voltage must be present.