Andrey Tasmaly

oh, forgot to mention, i actually popped the cover off on the fuel pump relay so i can see it work, well when the car is gonna start, the fuel relay engages, but when it doesn't start the relay does not engage, well i was sure at that point it was the relay, so i manually pushed on the relay mechanism to manually engage it, i hear the pump starting to pump when i do that, but the car still wont start, to me it seems like the feed doesn't even come to the relay, so im still guessing the crack shaft position sensor cuts the feed to that fuel pump and everything else that is needed to start the engine. (spark and everything else..)

jdevoid

I had same issue on 06 4.2 A6 and it was speed sensor (aka crankshaft sensor??)

RickKlint

I'm having a similar problem as some of the people on here. My issue is a little different. I have no issues getting it started if the car hasn't been driven in a while. I can drive it to work (about 20 miles) and drive it home after, but, If I stop to get something from the store and turn it off and then come back out and start it up again (starts up fine) in about 3-5 minutes the motor dies while I'm driving it. once after 5 minutes it started back up. The other time I had to jump start it because the battery drained after about 7 attempts to start it up.
As far as the warning lights, nothing!
The first time I had the belt changed on it. I figured this might be the issue and it was past the time I should have replaced it.
I changed the fuel relay thinking that might be the problem. It's still happening.
The only thing I can add is that I had an Alpine CarPlay stereo installed about a month ago.
Any advice would be greatly appreciated.

Robert Miranda

Old post I know sorry. Did you ever figure your issue? I'm now having the exact same issue. Car starts fine then it just seems like power is cut off. Then if I leave it a while with the key in the on position the check engine light comes on then i hear the pump priming up like it just got power

RickKlint

Hi,
It ended up being the crank sensor. My bad, I should have come back and posted how It was fixed.

Robert Miranda

Thanks!!! Did you get a code on vag com or vcds? I dont get anything lol but I was suspecting crank sensor as well lol

RickKlint

I didn't have VAG-COM at the time so I don't if it did or not.

BidgeeRoad

For me (C5 A6) it was the purge regulator valve. No codes after the first tow. P1426 (and P1453, P1458) after the second tow. Replacing the purge regulator valve fixed the problem.