[trojannate]

I recently purchased a used 2001 1.8 Liter 180 HP Audi TT. I drove it for a couple of weeks before putting in a K&N Air Filter. I do this with all of my vehicles and it has typically made a difference in performance.

However, this air filter seems to be causing either the MAF or Oxygen sensors to detect a change in air flow and cause my Check Engine light to come on repeatedly.

I called K&N and they said this is common and to disconnect my negative battery terminal for two hours, then reconnect in order to reset the computer. This will allow the computer to adapt to the new air flow and measure new low and high values.

However, I did this twice - once disconnecting the battery for three hours, the next time for an entire night. In both cases, the Check Engine light returned in a short period of driving time.

So, today I decided to put in the old, stock filter and see if it made any difference, or to tell if possibly one of my sensors was bad. As soon as I put it in, I took it out for a drive and the car ran rough and accelerated sluggishly (like there was vaccuum leak) but only for the first few minutes. The check engine light was flashing on and off and I was about ready to turn around on my test drive when the light went off and the engine began to run more smoothly.

My acceleration picked up again and the engine seems to be running great. No Check Engine light so far.

It makes me think the K&N truly is at fault, though I was starting to doubt it.

Has anyone had any similar troubles with this filter on an Audi TT?