So I crossed jumper cables on my 1999 audi a6 avant and now whenever I start it it stalls out. It seemed like it had a bad battery because it would die a lot and I would have to recharge it. WHen I can get it running it wont go over 3000 rpms and wont go over 15 to 20 mph. ANy ideas what happened and how much itll be to fix it?

 

is the battery light on constantly? also check for fault codes.

chances are the alternator has been damaged. also check the main fuse and the main relay

 

No but the check engine light is on. The alternator might be damaged but I doubt it because when I start it I can keep it running by flooring the gas and the battery will still keep starting it unless I let it sit for a week or 2 and the battery won't hold a charge and ice checked all the fuses they're all good. If I hold the gas at 1500 rpms for a few minutes it'll idle but if I just start it it dies out instantly

 

Wondering what the fix was. Just did the same thing and car is behaving the exact same way.

 

Did you ever find a solution?