09S5

2009 S5


Car has 50k miles


2 weeks ago changed all spark plugs car was running fine .


Today added a bottle of sea foam to the tank .


Got fuel also.


And now check engine light on.


I'm thinking gas cap?


Anybody else ???

09S5

car runs fine on highway.

SloopJohnB@mac.com

So the CEL light is on. Doesn't mean JACK unless you have a code. If you have to ask how to pull the codes, you haven't or can't read and you should just take it to the dealer and BOHICA.

09S5

Code is p0421.

09S5

I cleared it out to see if it comes back.

uberwgn

I would run all the additive out. Clear the code again, if necessary. Continue driving and see if the codes re-appears.

09S5

Uberwgn thanks for the information.


I purchase a code reader from autozone for about $ 80. I was surprise it worked on the Audi.
I was under the impression I needed a VAG-COM or Audi tools

uberwgn

By mandate, a code reader should be able to read any car sold in the USA. Problem is, the information (codes) they return is typically less specific than the info passed back by VCDS. I guess it would be interesting to see what info the VCDS system passed back in comparison...


For now, I'd just drive the car and not worry about it unless the code re-appears.

09S5

What does this means???

09S5

o2 sensor?
driver side before the c.c.?