i just got my a4 quatro 2.8 like 3 weeks ago and i was driving 2 work 2day and my check engine light came on so all day at work i was just browsing online cause it was bugging the crap outta me cause i like my stuff 2 work right and i was wondering what possible reasons u think it was !! i asked my dad he said it might have been if the gas cap was left very loose which it was when i just checked and im still gonna have it checked and every thing and still runs the same but i was thinking it was a o2 sensor or something or this seems very common with this car from what i saw online tell me what u think cause i dont know cause im used 2 drive a nissan 300zx tt and this never happened 2 me

 

You gotta get it scanned. Theres like 1000 posible causes for a check engine light. One of the most common however is the gas cap being loose. In your case you will probably have a fault for evap system leak detected. Check to be sure thou.

 

best thing to do is get a vw/audi scanner off ebay for 40 bucks. best money you can buy, diagnose and clear the codes. just wondering what grade of gas are you putting in. i ask because in both my bimmer and a4 my dad put in 87 octane when they both take premium, the check engine light came on, on the audi i used my scanner and found the knock sensors were going off. just some food for thought, but really get the scanner, looks cheap but really works.

 

http://search.ebay.com/AUDI-CODE-REA...tsearchZSearch

 

Autozone scans for free. But those code readers area good thing to have.

 

yeah thx it went off but he said i might need 2 clean the carbon build up off my egr valve and i only put premium in my car same with my 300zx tt

 

it doesnt even go on any more i keep putting 89 in