Hard Failures

All vehicles are equipped with a permanent fault memory. If a failure occurs in monitored sensors and components, they store a hard failure in memory.

Hard failures of monitored sensors and/or components cause Malfunction Indicator Light (MIL) to come on and remain on until problem is repaired. If MIL comes on and remains on during vehicle operation, cause of failure must be determined.

If failures are present for more than 5 seconds, they are stored as Diagnostic Trouble Codes (DTCs) and will be displayed as a permanent failure even if failure is not present during DTCs display. Failures affecting oxygen sensor control can only be read accurately after a test drive of at least 10 minutes.