With Generic Scan Tool

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

Recommended special tools and equipment
- V.A.G 1526 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:
- Fuel Pump Relay -J17- must be OK
- Ignition switched off.

Test sequence






- Disconnect 4-pin harness connector (black) to Heated Oxygen Sensor (HO2S) -G39- (item no. 1).

Vehicles > 08.99






- Check resistance for sensor heater at connector to oxygen sensor terminal 1 + 2.
Specified value: 1.0 to 24.2 Ohms (at room temperature)

Vehicles 09.99 >






- Check resistance for sensor heater at connector to oxygen sensor terminal 1 + 2.
Specified value: 1.0 to 5.0 Ohms (at room temperature)

Contine for all vehicles

If specified value is not obtained:
- Replace Heated Oxygen Sensor (HO2S) -G39- bank 1 before catalytic converter.
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code.

If specified value is obtained:
- Check Ground (GND) activation of oxygen sensor heater.
- Connect test box to control module wiring harness, connect test box for wiring test.

Vehicles > 08.99






- Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Terminal 2 + socket 12
Wire resistance: max. 1.5 Ohms

- Check wires for short circuit to B+ and to Ground (GND).
Specified value: Infinite Ohms

- Check wire between 4-pin connector terminal 1 and Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 Ohms

If no malfunctions are found in wires:
- Replace Motronic Engine Control Module (ECM) -J220-.

Vehicles 09.99 >






- Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Terminal 2 + socket 27
Wire resistance: max. 1.5 Ohms

- Check wires for short circuit to B+ and to Ground (GND).
Specified value: Infinite Ohms

- Check wire between 4-pin connector terminal 1 and Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 Ohms

If no malfunctions are found in wires:
- Replace Motronic Engine Control Module (ECM) -J220-.