Oxygen Sensor Heater For Oxygen Sensor Before Three Way Catalytic Converter (TWC), Checking

Oxygen Sensor Heater For Oxygen Sensor Before Three Way Catalytic Converter (TWC), Checking

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.

Recommended special tools and equipment
- V.A.G 1526 portable multimeter or V.A.G 1715 multimeter
- V.A.G 1594 connector test kit
- Wiring diagram

Test requirements





- The respective fuses of Heated Oxygen Sensor (HO2S) -G39- must be OK:
- Ignition switched off.

Vehicles with engine code AEB





- Disconnect 4-pin harness connector (brown) to Heated Oxygen Sensor (HO2S) -G39- (-1-).





- Check oxygen sensor heater for continuity at connector to Heated Oxygen Sensor (HO2S) terminals 1 + 2.
Specified value: 2.5 to 10 ohms (at room temperature)

Vehicles with engine code ATW





- Disconnect 4-pin harness connector (black) to Heated Oxygen Sensor (HO2S) -G39- (-1-).





- Check oxygen sensor heater for continuity at connector to Heated Oxygen Sensor (HO2S) terminals 1 + 2.
Specified value: 2.5 to 10 ohms (at room temperature)

Vehicles with engine code AWM





- Disconnect 6-pin harness connector (black) to Heated Oxygen Sensor (HO2S) -G39- (-2-).





- Set multimeter for resistance measurement and connect it to terminals 3 + 4 at connector for oxygen sensor. Check oxygen sensor heater for continuity.
Specified value: 2.5 to 10 ohms (at room temperature)

Continued for all vehicles
If an open circuit is found in the oxygen sensor heater:
- Replace Heated Oxygen Sensor (HO2S) -G39- before catalytic converter
- Erase DTC memory of Engine Control Module (ECM)
- Generate readiness code

If oxygen sensor heater has continuity:
- Check voltage supply and wiring

Checking voltage supply and wiring

Vehicles with engine code AEB





- Set multimeter for voltage measurement and connect it to terminals 1 + 2 at connector to control module.

Vehicles with engine code ATW





- Set multimeter for voltage measurement and connect it to terminals 1 + 2 at connector to control module.

Vehicles with engine code AUG, AWM





- Set multimeter for voltage measurement and connect it to terminals 3 + 4 at connector to control module.

Continued for all vehicles
- Start engine, and let run at idle.
- Measure voltage supply
Specified value: oscillating between 0.0 and 12.0 V

If there is no voltage:
- Connect multimeter for voltage measurement to
Engine codes AEB, ATW: Terminal 1
Engine code AUG, AWM: Terminal 3 of connector and engine Ground (GND).
Specified value: 11 to 15 V

If there is no voltage again:
- Check wire connections from
Engine codes AEB, ATW: Terminal 1
Engine code AWM: Terminal 3to Fuel Pump (FP) Relay -J17- according to wiring diagram.

If voltage was approximately same as battery voltage:
- Switch ignition off.
- Connect test box to control module wiring harness, connect test box for wiring test.
Engine Control Module ECM) is not connected.

Vehicles with engine code AEB





- Check wire between test box and 4-pin connector for open circuit according to wiring diagram.
Terminal 2 + socket 27
Wire resistance: max: 1.5 ohms

Vehicles with engine code ATW





- Check wire between test box and 4-pin connector for open circuit according to wiring diagram.
Terminal 2 + socket 5
Wire resistance: max: 1.5 ohms

Vehicles with engine code AWM





- Check wire between test box and 6-pin connector for open circuit according to wiring diagram.
Terminal 4 + socket 5
Wire resistance: max: 1.5 ohms

Continued for all vehicles
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM)