I know someone who says the check engine light goes on and off. This car is an s5 na. Car idles at 750 no leaks and has power. What would cause the light to do that? Is it something drastic? I know n odamaged engine internals cause that.

 

pull codes.

 

how do you pull codes?

 

http://www.banzai-racing.com/FD&S5_error_codes.htm

 

i dont have a diagnostic machine.

 

You have an S5 and there is a "single wire check connector" near the leading coil and it is this wire which needs to be grounded, followed by turning the key to on, and then looking at the CEL for code flashes.

 

Oh right. i know what you are talking about now. its that green terminal looking connector. Thanks!