Oxygen Sensors Before Catalytic Converter, Checking Signal Wire and Activation

Diagnostic Procedures

Oxygen Sensors before Catalytic Converter, Checking Signal Wire and Activation

Component location, refer to Repair Information.

• Oxygen sensor signals are monitored via On Board Diagnostic (OBD).

- Check DTC memory. If an oxygen sensor malfunction is displayed.

- Disconnect respective harness connector for oxygen sensor.





2 4-pin harness connector for Heated Oxygen Sensor (HO2S) 2 (G108) and Oxygen Sensor (O2S) 2 Heater (Z28) before catalytic converter, bank 2
3 4-pin harness connector for Heated Oxygen Sensor (HO2S) (G39) and Oxygen Sensor (O2S) Heater (Z19) before catalytic converter, bank 1

- Perform voltage measurement between terminals 1 (signal wire) and 5 (sensor Ground -GND-) of connector at wiring harness using portable multimeter (VAG1526) (measurement range 2 V).





- Switch ignition on.

Specified value: 450 ± 50 mV

- Switch ignition off.

If specified value is not obtained, check wire connections.

If specified value is reached, replace respective Heated Oxygen Sensor (HO2S) (G39)/Heated Oxygen Sensor (HO2S) 2 (G108).

Wire Connections, Checking

- Connect test box (VAG1598/31) to wiring harness of Engine Control Module (ECM), refer to Repair Information.





- Check the following wire connections for open circuit, short circuit to B+ or Ground (GND).

Heated Oxygen Sensor (HO2S) (G39) before catalytic converter bank 1





- Repair open circuit in wiring or short circuit if necessary.

- Check wire connections to each other for short circuit.

- If wire connection is OK, replace Engine Control Module (ECM), refer to Repair Information and generate readiness code again => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.

Heated Oxygen Sensor (HO2S) 2 (G108) before catalytic converter bank 1









- Repair open circuit in wiring or short circuit if necessary.

- Check wire connections to each other for short circuit.

- If wire connection is OK, replace Engine Control Module (ECM), refer to Repair Information and generate readiness code again => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.