VAG-COM
Audi Issues & Problems

Concert and Symphony Radios
These are made by Matsushita.   The Concerts have blatant bugs in the diagnostic protocols.   We've added one work-around to the low level protocol drivers that works in some, but not all  Concerts, and it is not 100% reliable in any case. 

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.

It appears that I suspect there is something not quite up to snuff in the Symphony's ability to drive the K-line. We've had some reports that they work better with non-optically isolated interfaces, and they may work better with the engine running (which means there is a higher voltage on the VBatt lines in the car).

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 care 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.  These ECUs (made by Hella) are so incredibly fussy about the protocol timing, I don't think there's any way to get them to work with a "dumb" interface and an application running in user-mode under Windows.  There may be a solution for these in the long term with a "smart" interface adapter or a kernel-mode driver, but for the time being, we have to say that VAG-COM is incompatible with them.