Diagnostic Procedure

DTC 27 Sub Heated Oxygen Sensor Circuit

DIAGNOSTIC PROCEDURE




NOTE: When other codes are output in addition to 27 at the same time, check the circuits for other codes first.
1. CHECK VOLTAGE OF TERMINAL HT2.
- If OK proceed to step 4.
- If not OK proceed to step 2.
2. CHECK RESISTANCE OF SUB HEATED OXYGEN SENSOR HEATER.
- If OK proceed to step 3.
- If not OK replace sub heated oxygen sensor.
3. CHECK FOR OPEN AND SHORT IN HARNESS AND CONNECTOR BETWEEN EFI MAIN RELAY AND ECM.
- If OK check and replace ECM.
- If not OK repair or replace harness or connector.
4. CHECK OPERATION OF SUB HEATED OXYGEN SENSOR HEATER.
- If OK replace sub heated oxygen sensor [1].
- If not OK check and replace ECM.

[1] It is probable that the oxygen sensor has deteriorated.