Diagnostic Procedure

DIAGNOSTIC PROCEDURE FOR DTC 27



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.