Lol, well.

From my Bentley manual:

P0302 - Cyl #2 misfire detected
P0642 - Knock control module malfunction
P0645 - A/C clutch relay control circuit

 

Everyone should stop helping you because youre being an idiot, we don't have over 1,000 posts because we like the mess with people, I can do that while Im sitting outside in the sun instead of in here on the computer... but anyway, you need to be more specific and answer my question.. Did you scan the ABS module or did you scan the engine computer? You said you have a CEL, CEL stands for "Check ENGINE light", do you have a check engine light or do you have an abs light? If you have an ABS light and those are codes from the ABS computer, then your codes do apply to the ABS but you shouldnt have called them CEL's, and hence why everyone is confused. If you have a Check engine light, a "CEL", and you scanned the engine computer then your scanner is giving the wrong description..

 

Also you're useless, use the damn search function. These cars have been out since '96, you're not covering anything new with your ******* misfire.

edit start reading: http://lmgtfy.com/?q=Audi+a4+p0642

 

Yeah something isn't right there. McGovs and BaseDrifter are correct about the codes, your scanner is reading them improperly. EDL stands for Electronic Differential Lock, which your car doesn't have. When you first plug it in, your scanner should automatically detect the platform, engine code, and ECU code from your car. Can you take a picture of this information and post it up? I have a feeling your scanner thinks your car is a different model and/or year.

No need to get pissy with these guys, they're just trying to help you diagnose the problems you're having.