We have been unable to locate a Trouble Bulletin regarding 1999 Audi A8 Quattro OBD II communication trouble. We recommend contacting Audi for more recent data, and/or discuss this matter with the State Smog Referee's Office (800) 622-7733.
The simplest problem could be loose wiring within the OBD II connector or blown fuse. The most complicated fault could be a problem with your Audi's Engine Control Computer (ECU).
If you can purchase an inexpensive Trouble Code reader (Pepboys or AutoZone carry them) go ahead and try connecting to your Audi's ECU via the OBD II connector. If the scanner lights up as it's connected to your vehicle this indicates there is power at the connector and the problem is more then likely with the signal wire between the OBD II connector and the ECU. If the scanner does not light up this might indicate either a loose or disconnected power or ground wire at the connector, and even the possibility of a shorted fuse. Check your Audi's fuse box for a fuse labeled DLC (Data Link Connector).
posted by SmogTips Support
