ok first off i have had this car for 3 weeks and search these threads daily .. i have learned alot with out being a member about these cars . so please take it easy .but i have a a4 b5 quattro its a 2000 160k miles just picked the car up its running 18 to 21 psi stock turbo no clue what tune borla exhaust system suspension control arms yoda yoda. but engine wise just a tune and i just put a cai on it and have a 007 dv on the way. but my issue is car has had a cel light on sense i got it went to run it says no link searched it and found its the aftermarket radio how do i go about checking the codes with the cd player being different ? also car runs rich if i rev it backfires a lil also after about a week puts a black spot on my bumper . but recently i got an exhaust leak fixed and can hear a hissing noise did a leak test found nothing its only over 10 psi i hear it thinking dv also just today if i floor it it like hit boost cut or somthing started jerking but runs awsome if a creep to 20psi or drive it normal ?? any advise on any of my questions greatly appriciated thanks

 

Hi Codey, welcome to AF.

You seem to be running into a problem that is common for newer Audis/VWs with aftermarket radios. The problem is that the wire carrying the diagnostics signal is often hooked up incorrectly and sees 12v instead of the data signal from the stock radio.

More reading (with a solution) here: Ross-Tech: VCDS: Afterrmarket Radio Problem

You should get that new DV in place ASAP and try to get vag com working. It is very difficult to continue diagnosing your problems without scanning for codes.

 

Yes it is thanks for the write up

 

man did what it said to do but still won't read codes I dunno if I clipped the right wire now? There saying it a grey wire with white stripe there is no wire that color on my stereo harness the wire in the third pin is green with blue stripe please any input

 

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ok here is an update no clue why im posting nobody posts back on here but anyways ..replaced front o2 sensor changes nothing . cleaned maf changed nothing so i bought a new coil and went threw them found coil 3 was bad so changed it ran a bit better no jerking any more ..next day started to do it again a lil so said heck with it rplaced all 4 coils no more jerking fixed that problem but still at right at 3200 rpm you can feel the car fall on its face like somthing is holding it back also if you rev the car with a full throttle rev it will back fire any input would be very very nice thanks

 

Did you ever get your vag com working? Any CEL's or idiot lights on? At what RPM does the backfire happen?

 

air bag light is on and the cel light is as well i have a code scanner but it always says link error have taken to a few places same deal one time it did read and said bank 1 sensor 2 o2 sensore just bought it yet to install . but the back fire happens if you rev it in neutral. for awhile it was sooting my back bumer but i replace the coils first o2 sensor and cleaned the maf and that stopped new dv will be here tomorrow i can hear a boost leak somewere tested and found none also hold a steady 20 psi most of the time the leak start at 8 psi and up but car falls on its face from 5 to 10 psi or if i stay out of boost its drastic at 3200 rpm

 

Where are you located? I have a boost leak tester if you'd like to borrow it.

 

I am located in Indiana? also if I download the vag com and get the cable will I be able to check for codes even though a code reader wont work?