Diagnostic Procedure

DIAGNOSTIC PROCEDURE

HINT: When other codes are output in addition to 27 and/or 29 at the same time, check the circuits for other codes first. If diagnostic trouble code 27 is displayed, check left bank sub heated oxygen sensor circuit, and if 29 is displayed, check right bank sub heated oxygen sensor circuit.

1. Check voltage of terminals HTL2, HTR2.
- If OK proceed to step 3.
- If not OK proceed to step 2.
2. Check resistance of sub heated oxygen sensor heater.
- If OK check and repair sub heated oxygen sensor hater circuit.
- If not OK replace sub heated oxygen.
3. Check operation of sub heated oxygen sensor heater.
- If OK replace sub heated oxygen sensor.
- If not OK check and replace engine control module.