Hard Failures

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

If malfunctions are present for more than 5 seconds, they are stored as Diagnostic Trouble Codes (DTCs) and will be displayed as a permanent malfunction even though the malfunction is not occurring at the time DTCs are displayed. Malfunctions that affect oxygen sensor control can only be read accurately after a test drive of at least 5 minutes.