Oxygen Sensor Heater For Oxygen Sensors 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 AUG, 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), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- 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 AUG, 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. Test Box, Connecting For Wiring Test

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 AUG, 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)