Hello everyone
I'm new to this forum. Looks like i can get a lot of useful information. One year ago I purchased an A4. 3.0 that required a ton of engine work. About ten months ago, my engine light came on and I had it looked at and the mechanic told me that it was my Cats that were not funcitioning properly. I spoke to previous owner and he never had such a problem, so I was skeptical. Car has 178K. I do mostly city driving only on weekends so car is not driven much, but last month, I took the car on the highway for the first time and then after a few days, my engine light disappeared for over one week. Afer more city driving it came on again. This past weekend, I took the car for a long trip and last night the engine light went off again. Both times, that this happened, my headlight on warning signal started working again. Any suggestions as to what might be causing this oddity? Electrical perhaps? Anyone have same experience? Your feedback and comments are most appreciated.

 

the amount of exhaust going thru the cats change on the highway vs city, your car needs cats. the headlight warning could just be a random electrical issue

 

Thanks Sean. I did some research and other people who have had the same problem cleaned or replaced their MAF and the problem seemed to go away. In other cases there was a leak in the vacuum line. The guy i bought the car from told me he never had problems with the CATS. In fact, when the computer was connected to my car it showed that the cats were running at high efficiency. I doubt very much it is the CATS at this point. Thanks for your input though. While it makes sense, I need to exercise other less costly causes. Have a great day.

 

what were the codes for the engine light?