I was fixes a notorious problem where my headlights suddenly stopped working on my B5 A4. In order to fix the problem you have to remove the switch on the steering wheel stalk and recondition the switch. That all went very well and I disconnected the battery to be safe.

Unfortunately, when I had to reposition the steering wheel to fasten the last two bolts, I had to put in the key to unlock the steering wheel AND... I forget to take it out before I reconnected the battery. there was a bit of arcing and things powered up and down for a moment since the key was in and I must have actually turned it forward a notch as well.

Things seemed fine, the head lights were now working again, proving I had fixed the problem correctly.

However, when I went to start the car (after clearing the SAFE from the stereo) the car wouldn't catch. I tried again and gave it a bit more gas and it was running barely and very rough. I shut it down and now I am very perplexed as to what I must have done. The best theory I have is that somehow the arcing at the battery terminal might have affected some of the electrical devices associated with the ignition system (ie spark and timing).

Any ideas? Does this sound familiar to anyone?

thanks,

- David

 

This follow-up is for anyone who might be interested in the outcome. It turns out that either / or the amount of time with the battery disconnected or perhaps on reconnection the ecu and/or throttle actuator/system did in fact need to be reset / calibrated with a VAG com or similar.

I don't have the unit so I paid someone else to do it for me but it is running nice and smooth now (and the headlights work!)