VAG-COM
Audi Issues & Problems

Concert and Symphony Radios
These are made by Matsushita.  Some of them appear to have bugs in the diagnostic protocols.   I have already added one work-around to the low level protocol drivers that works in some, but not all  Concerts.   Some Symphonies work perfectly (like the one I purchased so I could pursue this issue).  Other Symphonies are do not communicate reliably.  I would like to get my hands on "flaky" Symphony Radio so I can investigate further.

Some Concerts occasionally get "stuck" in an undesirable mode after attempting communications.  If your Concert get's "stuck", the way to reset it is to remove all power from from the radio for at least 10-15 seconds. This can be done by:

  • Removing the radio from the car.

  • Disconnecting the car's battery

  • Pulling the fuse for the radio.

Note: Some radios will require you to enter the "security code" using the radio's front panel after loosing power.  See the your owner's manual for the radio for instructions.

1994-1997 C4 (A6/S6) Instrument Clusters
These have a high bit-error rate.  I suspect they use a software-UART and "stretch" bits sometimes.  The error-detection/correction logic built into VAG-COM's low-level protocol drivers as of version 0.70 seems to take car of this in a majority of cases,  but I still had  few reports of customers not being able to communicate with these clusters.    In version 0.75 or or newer, please ensure that Char Int on the Options Screen is set to approximately 3 (which is the default).   On some PC's, it may be necessary to adjust this value to something other than 3.  On very fast PC's try a higher value.  On very slow PC's, try something less.

1992-1994 2.6L V6 Engine (non-US only) 
VAG-COM cannot communicate with some of these ECU's.   I do not yet know what the problem is.  The DEBUG files don't tell me enough.  It looks like some sort of protocols timing issue, and that means I have to get an ECU to play with.   Unfortunately, they are hard to find in the US since we never got the 2.6L V6 here.   


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