Heated Oxygen Sensor and Oxygen Sensor Control before Catalytic Converter, Checking

Heated Oxygen Sensor And Oxygen Sensor Control Before Catalytic Converter, Checking

Recommended Special Tools, Workshop Equipment, Testers, Measuring Instruments and Auxiliary Items
- V.A.G 1526 portable multimeter or V.A.G 1715 multimeter
- Adapter set V. A. G 1594
- Wiring diagram

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor (H02S), use only gold-plated terminals.

Test Conditions
- Corresponding Heated Oxygen Sensor (HO2S) -G39- fuses must be OK
- Battery voltage must be at least 11.5 V.
- All electrical consumers such as, for example, lights and rear window defroster must be switched off.
- The parking brake must be applied, otherwise the daytime running lights are switched on.
- If the vehicle is equipped with an air conditioning system, this must be switched off.
- The Ground (GND) connections between engine and body must be OK.
- Exhaust system must be properly sealed between catalytic converter and cylinder head.
- Oxygen sensor heating for oxygen sensors in front of catalytic converter must be OK, checking.

Checking Primary Voltage

Engine Codes AMU, ATC







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







- Use adapter cables from V.A.G 1594 to connect multimeter to terminals 3 + 4 (ECM connector) for voltage measurement.
- Start engine and measure primary voltage.

Specified value: 0.40 to 0.50 V

- Switch off ignition.

Engine Codes AWP, BEA
- Disconnect 6-pin connector to Heated Oxygen Sensor (HO2S) -G39-.







- Connect multimeter between terminal 1 and 5 for voltage measurement.
- Switch ignition on and measure primary voltage.

Specified value: 0.40 to 0.50 V

- Switch off ignition.

Continuation for All Vehicles

If the specification is not obtained:
- Test oxygen sensor wires.

If the specification is obtained:
- Replace Heated Oxygen Sensor (HO2S) -G39- in front of catalytic converter.
- Erase DTC memory of ECM. Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Generate Readiness Code

Oxygen Sensor Wires, Checking

Engine Codes AMU, ATC
- Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.







Wiring resistance: max. 1.5 Ohms







Engine Codes AWP, BEA
- Check wires between test box and 6-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.







Wiring resistance: max. 1.5 Ohms







Continuation for All Vehicles
- Also check wires for short circuit to B+ and Ground (GND).

Specified value: Infinity Ohms

If no fault is detected in the wiring:
- Replace Motronic Engine Control Module (ECM) -J220-