With Generic Scan Tool

Oxygen sensor heater for oxygen sensors 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 multimeter or V.A.G 1715 multimeter
- V.A.G 1594 Connector test set
- Wiring diagram

Test requirements






- The respective fuses of Heated Oxygen Sensor (HO2S) -G39- and Heated Oxygen Sensor (HO2S) 2 -G108- must be OK:
- Ignition switched off.

Test sequence
- Disconnect 4-pin harness connector to the respective oxygen sensor:






Heated Oxygen Sensor (HO2S) -G39-, bank 1 4-pin harness connector (black, arrow).






Heated Oxygen Sensor (HO2S) 2 -G108-, bank 2 4-pin harness connector (black, arrow).

NOTE:
- To reach this harness connector, remove coolant reservoir attachment screws and tilt coolant reservoir to the side. The coolant hoses remain connected.
- Bank 1 = Cylinder bank 1, in direction of travel, right
- Bank 2 = Cylinder bank 2, in direction of travel, left

Vehicles with engine code AHA






- Measure resistance for sensor heater at connector to oxygen sensor terminal 1 + 2.
Specified value: 0.0 to 19.9 Ohms

Vehicles with engine code ATQ






- Measure resistance for sensor heater at connector to oxygen sensor terminal 1 + 2.
Specified value: max: 200 Ohms

Continuation for all vehicles
If specified value is not obtained:
- Replace the respective oxygen sensor:
- Heated Oxygen Sensor (HO2S) -G39-, bank 1, item 1
- Heated Oxygen Sensor (HO2S) 2 -G108-, bank 2, item 15
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data.
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

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






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

Vehicles with engine code AHA






Vehicles with engine code ATQ






Continuation for all vehicles
- Also check wires for short circuit to B+ or Ground (GND).
Specified value: Infinity 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-.