Repair procedures (plant/service)

This malfunction is detected during the active test. The active test is triggered by the trim control diagnosis function (trim controller fault code stored in the control module's fault memory!)

1. Initiate system test for reversed O2 sensors. Follow instructions for system test.
2. If the system test fails to produce a result then
3. Visual inspection of wiring and plugs
4. Electrical check of wiring
5. Replace wires or plugs as indicated
6. Check exhaust system upstream from downstream (post-cat) O2 sensor for leaks
7. Replace downstream (post-cat) O2 sensor
8. Replace upstream (pre-cat) O2 sensor
9. Replace control module