Hard Failures
NOTE:
Scan Tester (VAG 1551) must be used to make full use of the self-diagnostic system capabilities.
All vehicles are equipped with a permanent fault memory. If a fault occurs in monitored sensors and components, they store a hard fault 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 (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 if malfunction is not present during DTCs display. Malfunctions affecting oxygen sensor control can only be read accurately after a test drive of at least 5 minutes.