Electrical Testing

Oxygen Sensor Connector:

SENSOR ELECTRICAL TESTS:
- Disconnect rear Oxygen Sensor connector(s), underneath the vehicle (beneath the driver and/or passenger front seats) using removable rubber access cover(s) in the floor pans. on right or left cylinder bank.
- Switch multimeter (Fluke 83 or equivalent) to resistance measuring range and connect between connector terminals 3 and 4 of the sensor connector.
^ Specified value: infinite ohms (no continuity).

If specified value is not obtained:
- Replace heated oxygen sensor.

If specified value is obtained:
- Switch multimeter to 0-2 volts measuring range and connect between terminals 3 and 4 of ECM harness connector.
- Switch ignition ON.
^ Specified value: 400 +/- 50 mV.

If specified value is not obtained:
- 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

Oxygen Sensor Connector:

- Check for continuity between terminal 3 of the harness connector for the sensor and test box socket C17 for both the right and left bank sensors.
^ Specified value: maximum 1 ohm.
- Check for continuity between terminal 4 of the harness connector for the sensor and test box socket: C20 for the right bank sensor or C21 for the left bank sensor.
^ Specified value: maximum 1 ohm.

If specified values are not obtained:
- Repair open or short circuit in wiring connection between sensor connectors and ECM connector C according to wiring diagrams.

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