Ihave a 2002 a6 2.7t check engine light came on. After a day it went away. Is this something i should worry about

 

if it comes back on then i would look at it. if it stays off i wouldnt worry

 

I had somthing like that happen to me, CEL would come on and then go off a few days later, than come on and go off again untill it stayed on. My cats where gone and the 02's couldnt read the air anymore, well they coudl but they were just reading bad air. hope this helps, if it is your catsa your looking at about 1500 a cat from the dealship, if you buy them used on here your looking at no more than 300 bucks . In all honesty, if this is what it is then yo have nothing to worry about except that you wont pass smog. If you have access to a vag that will let you know right away. Or have the dealship vag it for you, thats how i found out