Oxygen Sensor After Catalytic Converter (Cylinders 1 - 3) - Interruption of Signal
P0140
Oxygen Sensor After 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 P0140 is stored by the DME control module when the sensor voltage is continuously between 400 mV and 500 mV for more than 400 seconds.
Conditions for the diagnosis of the oxygen sensor signals:
- Sensor heating active.
P0140:
NOTE: When DTC P0140 is stored, DTC P1117 may be stored as well.
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 after 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 rpm for 3 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 after catalytic converter.
Display: Voltage fluctuations between 100 mV and 800 mV.
- Oxygen sensor OK.
3 Check oxygen sensor heating.
1. Remove HO2S connector 1 after 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