Hi all I'm new to this forum and here to ask a question I can't find the answer to. I recently removed the IAT sensor in my 2001 A4 1.8 to do a quick cleaning. I was very gentle and highly doubt I damaged the sensor. When I turned the car back on the CEL came on, which is when I realized I failed to plug back in the wiring to the sensor. I turned the car off, plugged the wiring back in and restarted the car but the light was still on. I don't have any kind of code reader so I disconnected the battery for about 10 minutes and plugged it back in which cleared the light.

I haven't driven the car since and won't get a chance to until tomorrow but I have a few questions...

1. Would the CEL stay on like it did, even after I plugged in the wiring, because the code was still present in the computer?

2. Did disconnecting the battery permanently clear the code or should I expect it to return? And if it does will driving the car for a while cause it to clear?

3. I am due for an NJ state inspection. Did I screw myself by disconnecting the battery? I've heard that it takes a while for the computer to reset before and inspection can be done.

Keep in mind that I am almost certain that the light was caused by forgetting to reconnect the wiring (unless something else in my car failed at that exact moment).

 

My thoughts:
1. the code was still present, after running the engine for a little while it probably would have cleared itself when the ECU received repeated valid values from the IAT sensor.
2. If it the code clears and doesn't come back after a couple of minutes then there is no reason to believe it will return later.
3. Cannot answer that one, here in Australia as long as there are no codes they don't look in the history.

Why did you pull the sensor anyway? Just doing some preventative maintenance or did you suspect a problem?

 

Just pulled it out quick to clean after I cleaned up the throttle body, I didn't suspect any problems. The light hasn't come back and I passed inspection today.

 

Ok, If you 'cleaned up the throttle body' then you probably manually moved the flap during the clean up. This needs to be reset. (called adaptation). I have 4 VAG cars, on 3 of them this can be done after you plug the throttle body & the IAT back in by turning the ignition on but not starting. You will here a whining noise. Thats the throttle body resetting the limits automatically. After about 45 seconds its done. For some reason on one model I have it would not do it and I had to trigger the adaptation sequence via the VCDS software. I hope provides some helpful information to what you experienced.

 

Thanks. Sorry I forgot to mention I actually did reset the throttle body prior to starting the car.