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View Full Version : Question Audi Cam Sensor error and 4 cylinder misfire after replacing battery



Mezza2023
14-08-2023, 08:48 PM
Hoping someone can help. I just replaced my battery yesterday on my Audi S4 B7 2007 Cabriolet and since then the car is rough idling and getting error codes for cylinder 2 ,4 7, 8 and P0345 P0340 Camshaft position Sensor "A" circuit. I've removed the water reservoir tonight as know I've moved a lot of cables in the harness making room to drop the battery in so suspect one is possibly broken ? (maybe??) I've put a voltage meter across pins 1 and 3 on the Cam shaft sensor (grey one under the water reservoir on a UK model, as I noticed the US models don't have the harness doubling back) and I'm only getting 2.44v is this normal I though I should get 5V ?

Any idea where to start to troubleshoot this further? It's really strange as I started the car straight after replacing the battery and it seemed to run just fine. Sat with it running for about 10 mins then decided to go for a drive round the block to clear the ABS errors. Its mostly down hill so I didn't really need to accelerate much, got to the end of the road and noticed it had no power and sounded rough, so turn round and headed home. Once I stopped could really tell it was running rough and having trouble even starting without applying some gas. Hooked up the diags and noticed these misfire codes. I've since connected VCDS and done a throttle body adaptation as I though maybe the car had learned something weird. I've since disconnected and reconnected the battery but its just the some.

Any help is appreciated, thank you in advance.

Crasher
15-08-2023, 01:31 PM
Damaging that design of harness is always a risk when changing the battery and an evil job to deal with, daft design.

Mezza2023
15-08-2023, 02:25 PM
It most certainly is, going to be fun to find the damage, wish me luck.