I installed a new stereo in my 2004 A4 1.8T last night, and this morning the car wouldn't start. It would turn over, but never fire up. Everything else works (including the new stereo). My initial thought was that it was a low battery, but the battery is fine. I next checked all of the fuses in the fuse box at the driver side end of the dash, and none of the fuses were blown. I did not disconnect my battery prior to installing the stereo. I quickly called two shops, and they both said it was either "an electrical problem or a fuel pump issue", but I can hear what I think is my fuel pump working, and since I installed the stereo last night, I assume it has to be "an electrical issue."

Any help would be appreciated, and I am not the greatest with cars so please make sure any suggestions are detailed enough to allow me to try it.

 

Did you try unplugging the stereo harness to see if the car will start? Could be an issue with the K wire.

 

I removed the aftermarket stereo and even replaced the factory stereo, and still it will not start.

 

Did you try checking to see if the ECU threw any codes?

 

I don't know how to check the ECU (or even what that really means). Any help you can give me is much appreciated.

 

Ok if you have no way of checking for codes, check all of the fuses because there are a few ECU fuses in the fuse box. Best way to check them is to use a continuity tester.

 

I did a visual inspection of each fuse, and they were all fine. I will try with a continuity tester. Are there any other fuses under the hood or anywhere else I should be testing? The only fuses I checked are the 40 or so fuses at the end of the driver side dash.

 

It ended up locking up my ECU, which needed to be reset. I tried resetting it at home by disconnecting the battery for a couple of hours and then stepping on the brakes to "drain" the system. But that didn't work. The shop I took it to ended up resetting the ECU and everything is back to normal.