Electrical Testing

SENSOR ELECTRICAL TESTS:
- Disconnect harness connector for Heated Oxygen Sensor (HO2S) signal wire.
- Connect multimeter(Fluke 83 or equivalent) between oxygen sensor signal wire and GND.
^ Specified value: infinite ohms (no continuity).

If NO:
- Replace HO2S.

If YES:
- Switch multimeter to 0-2 volts measuring range and connect between signal wire connector (to ECM) and GND.
- Switch ignition ON.
^ Specified value: 400 +/- 50 mV.

If NO:
- Check wiring to ECM.

WIRING CHECKS:
- Switch ignition OFF.
- Connect VAG 1598/19 test box to ECM wiring harness. Refer to Computer and Control Systems, System Diagnosis, VAG 1598 Pin Out Box Connecting. Connecting VAG 1598/31 Test Box

Engine Control Module Connectors:

- Check for continuity between HO2S 1 (right bank, G39) signal wire and test box socket A20.
^ Specified value: maximum 1 ohm.
- Check for continuity between H02S 2 (left bank, G108) signal wire and test box socket A21.
^ Specified value: maximum 1 ohm.

If specified values are not obtained:
- Repair open or short circuit in wiring connection between connector in engine compartment and ECM connector A terminal 20 and/or 21, according to wiring diagrams.

If there is no malfunction in wiring connection:
- Replace ECM.