Oxygen Sensor Heating 1 After Catalytic Converter - Above Upper Limit

P1105

Oxygen Sensor Heating 1 After Catalytic Converter - Above Upper Limit

Function
The heated oxygen sensor (HO2S) generates a current signal starting at approx. 300 °C that determines the fuel/air mixture. This signal is used for the regulation of fuel injection. The oxygen sensor is heated to bring it quickly to operating temperature to start oxygen sensing earlier.

Diagnosis conditions
When oxygen sensor heating has been on for 400 sec., when no DTC "Oxygen sensor heating - below lower limit" is stored in the memory.

P1105-P1110:

NOTE: Heating of H02S (1 and 2) after the catalytic converters is supplied by an output stage. When there is a fault in the heating circuit, both heating circuits (1 and 2) are always stored in the memory as faulty.

Oxygen sensor 1 - cylinders 1 to 3
Oxygen sensor 2 - cylinders 4 to 6

Connector color gray - after catalytic converter
Connector color black - ahead of catalytic converter Wiring Diagram

Wiring Diagram







Diagnosis Procedure







1 Check resistance of H02S heating.

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

2 Check HO2S and wiring from DME control module to disconnection points of HO2S 1/2 ahead of catalytic converter for short to B+.

1. Remove connector of HO2S 1/2 after catalytic converter.
2. Start engine and run at high speed for 3 minutes.
3. Connect voltmeter at sleeve to connector, pin 1 (positive), and pin 2.
Display: battery voltage

Connect voltmeter at sleeve to connector, pin 2 (positive), and ground.
Display: approx. 0 V

4. Switch off engine.
5. Remove DME control module connector.
6. Remove ignition, injection and HO2S heating relay and bridge terminals 30 and 87.
7. Connect voltmeter at sleeve to HO2S connector, pin 2 (positive), and ground.
Display: 0 V