Hi all - I have just replaced my battery and now my car is throwing p0300 p0301 p0302 codes. These are misfire codes and I was wondering if I really have to go to the local stealership and have my ecu reset with the proper idle settings, etc.

Many thanks,

Jeff

Is the car running a bit rough? How replaced the battery? I am thinking in the battery replacement that you may have had a couple of plug wires loosened or strained to the point they are weak. You can clear the codes by pulling the main fuse under the hood and waiting a minute to reconnect.

Bruce - thanks for your reply.

A bit of background - my MAF sensor has been throwing me a p0171 code and have cleaned it a bit - just ordered a new one. Would I be incorrect in thinking a fouled up MAF could cause the cylinders to misfire or is that a result of lack of power from the battery due to a bad ground, etc.

Best,

Jeff

Bruce, as far as running roughly - after turning the key the battery meter will go from 14 to about 12 and eventually after a few seconds dies. After restarting another 2 or three times the car will start and idle roughly then smoothly. As far as running roughly once it begins to idle smoothly it runs fine.

Thanks again...

JJS

Good grounding at all points is essential. I am concerned about the voltage dropping from 14 to 12. Check out the grounds first. Then have the alternator checked. The internal voltage regulator could be starting to go.

My question should not have been How but who replaced the battery?

Bruce - my new battery was installed by my mechanic who specializes in imports.

I have ordered a new MAF sensor that I can install myself and I am hoping that will cease the P0171 code I am getting.

As far as the P0300, P0301, and P0302 I will have the mechanic check the ground and test the alternator.

As far as getting my ECU reset I am hearing conflicting things from lots of my friends and on the internet. So, when replacing a battery for an Audi or other German import does the car have to go back to the dealership to have the idle codes and other info reprogrammed??

Thanks again for your prompt responses as I am learning quite a bit about my A4.

Jeff

Actually the cars computer will learn that on it own again unless there is a sensor that is not giving it correct information to work with.

i had my battery replaced in a 2000 vw passat v6 by walmart and nothing happened as a result. works fine, no codes or anything. i know before i replaced it, my power windows were acting funky...