P0150

P0150
Oxygen Sensor ahead of Catalytic Converter Short Circuit of Wires or Limited Voltage Increase (Cylinders 4 - 6)

Function
To diagnose the readiness for operation of the oxygen sensors, the position of the sensor voltage is evaluated (in case of certain faults or conditions, the diagnosis is disabled).

Diagnosis Conditions
Diagnostic Trouble Code P0150 is stored on the Engine Control Module (ECM) when a voltage increase of the oxygen sensor between 60 mV and 400 mV for more than 8 seconds is detected by the ECM and when the sensor voltage behind the catalytic converter exceeds 350 mV.

This fault also occurs when the voltage value of a cold oxygen sensor is between - 40 mV and + 40 mV (short circuit of wires).

Conditions for the diagnosis of the oxygen sensor signals:
- Sensor heating is active.
- Oxygen sensing is active.
- Oxygen sensor voltage behind catalytic converter > 350 mV.
- No Secondary Air Injection.
- No faults detected for fuel tank ventilation and Secondary Air Injection.

NOTE: When DTC P0150 is shedded, a non-shedded fault P1121 will be stored as well. This non-shedded fault is not an actual fault.





Diagnosis Procedure
Check oxygen sensor.
1. Heat the oxygen sensors (road test car under load or run engine without load at high engine speed).
2. Connect system tester or scan tool and read voltage of oxygen sensor 2 ahead of catalytic converter. Specified value: Voltage fluctuations between 100 mV and 800 mV.

- If voltage 100 mV - 800 mV --> Oxygen sensor OK.
- In case of a displayed value near 0 V, a short circuit between the signal wire and the sensor ground has occurred.

3. Remove oxygen sensor connector 2 ahead of catalytic converter.
4. Connect voltmeter at sleeve to pins 3 and 4. Specified value: 450 mV.

- If voltage out of spec --> Replace oxygen sensor.
- If specified value: approx. 0 V --> Check wiring harness.
- If the wiring harness is OK, remove all oxygen sensor connectors and perform measurement of item 4 on all oxygen sensors.

Check wiring harness..

NOTE: For this measurement, all other oxygen sensor connectors must be removed.

1. Remove oxygen sensor connector.
2. Remove ECM connector.
3. With ohmmeter measure resistance between ECM connector pin 18 and oxygen sensor connector pin 4. Specified value: < 5 ohms
- If not: Replace wiring harness.
4. With ohmmeter measure resistance between ECM connector pin 46 and oxygen sensor connector pin 3. Specified value: < 5 ohms.

Check ECM final stage.
1. Install ECM connector.
2. Remove oxygen sensor connector 2 ahead of catalytic converter.
3. Connect voltmeter at sleeve to pins 3 and 4.
4. Switch ignition on.
- Specified value: approx. 450 mV
- If reading < 400 mV or > 500 mV: Replace ECM.