P0140

P014O
Oxygen Sensor Behind 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 (in case of certain faults or cofldition5, the diagnosis is disabled).

Diagnosis Conditions:
Diagnostic Trouble Code P014O is stored in the Engine Control Module when the sensor voltage is between 400 mV and 500 mV for more than 400 seconds without interruptions.

Conditions for the diagnosis of the oxygen sensor signals:

Sensor heating is active.

NOTE: When DTC P0140 is stored, DTC P1117 may be stored as well.

Wiring Diagram:




Diagnosis Procedure:






1. Check wiring harness.
1. Remove all the four oxygen sensor connectors.
2. Switch ignition on.
3. Connect voltmeter at sleeve to pins 3 and 4 of oxygen sensor connector 1 behind catalytic converter.

Specified Value: approx. 450 mV.

4. Connect voltmeter at sleeve to pin 3 and ground.

Specified Value: approx. 720 mV.

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

Specified Value: battery voltage.

If the measurement according to items 3, 4, and 6 does not show the specified values, remove ECM connector and check wires for continuity.

If no continuity can be detected, repair wiring harness. If continuity OK, replace ECM.

2. Check function of oxygen sensor.
1. Heat the oxygen sensors (road-test car under load or run engine without load at high engine speed).
2. Connect Porsche System Tester 2 or scan tool and read voltage of oxygen sensor 1 behind catalytic converter.

Specified Value: Voltage fluctuations between 100 mV and 800 mV.

=> Oxygen sensor OK.

3. Check oxygen sensor heating.
1. Remove oxygen sensor connector 1 behind catalytic converter.
2. Connect ohmmeter on pin side to pins 1 and 2 of the oxygen sensor connector.

Specified Value: 1.8 - 2.5 Ohms at 20°C.

3. Connect ohmmeter on pin side to pin 1 and the oxygen sensor housing.

Specified Value: Infinity Ohms.

4. Connect ohmmeter on pin side to pin 2 and the oxygen sensor housing.

Specified Value: Infinity Ohms.