Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Interruption of Signal

P0134

Oxygen Sensor Ahead of Catalytic Converter (Cylinders 1 - 3) - Interruption of Signal

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

Diagnosis conditions
Diagnostic Trouble Code P0134 is stored by the DME control module when the sensor voltage is continuously between 400 mV and 600 mV for more than 5 seconds.

Conditions for the diagnosis of the oxygen sensor signals:
- Sensor heating active.

P0134:

NOTE:
- When DTC P0134 is stored, DTC P1115 may be stored as well.
- P0154 is also stored at the same time if there is an open circuit to the common sensor ground.

Wiring Diagram







Diagnosis Procedure







1 Check wiring harness.

1. Remove all four HO2S connectors.
2. Switch on the ignition.
3. Connect voltmeter at sleeve to pins 3 and 4 of HO2S connector 1 ahead of catalytic converter.
Display: approx. 450 mV

4. Connect voltmeter at sleeve to pin 3 and ground.
Display: approx. 720 mV

5. Start engine and run at high speed for three minutes.
6. Connect voltmeter at sleeve to pins 1 and 2.
Display: battery voltage

If the measurement according to items 3, 4 or 6 does not show the specified values, remove DME control module connector and check wiring for continuity.

If no continuity can be detected, repair wiring harness.
If continuity exists, replace DME control module.

2 Check function of oxygen sensor.

1. Heat the oxygen sensors (road test car under load or run engine without load at high rpm).
2. Connect Porsche System Tester 2 or scan tool and read voltage of oxygen sensor 1 ahead of catalytic converter.
Display: Voltage fluctuations between 100 mV and 800 mV.
- Oxygen sensor OK.

3 Check oxygen sensor heating.

1. Remove HO2S connector 1 ahead of catalytic converter.
2. Connect ohmmeter on pin side to pins 1 and 2.
Display: 1.8 - 2.5 ohms at 20 °C.

3. Connect ohmmeter on pin side to pin 1 and HO2S housing.
Display: Infinity ohm

4. Connect ohmmeter on pin side to pin 2 and HO2S housing.
Display: Infinity ohm