H27 - Attempt to Generate DTC 136, 172, or 176

- Key "OFF".

- Heated Oxygen Sensor (HO2S) disconnected.

- Jumper HO2S circuit at the HO2S vehicle harness connector to battery negative post.

- Rerun Engine Running Self-Test. Key ON Engine Running (KOER) Self-Test

- Is Diagnostic Trouble Code (DTC) 136, 172 or 176 present?

Yes -- Remove jumper.

With Mass airflow sensor, go to H30. H30 - HO2S Check

With Manifold absolute pressure sensor, go to H28 H28 - Check MAP Sensor For Vacuum Leak

No -- Remove jumper. Reconnect HO2S. Disconnect Powertrain Control Module (PCM) 60 pin connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary. If OK Replace PCM. Drive vehicle 5 miles/55 mph. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)