CEL Code...

[geoshu]

Had Autozone run my Check engine light again, it gave the code P2181. I couldn't find anything on the Bentley manual, oddly, for my engine size. The receipt Autozone gave me suggested changing the ECT sensor and/or radiator or water pump.

I changed the ECT sensor months back, that didnt help, and I really dont want to buy a new radiator or water pump. Anybody know what could be wrong with either? Car runs just fine, never overheats, warms up good...I'm clueless.

[FourRings80]

P2181= cooloing system performance

Imo

1) Did you change the coolant temperature sensor close to the firewall?

http://www.audiworld.com/tech/eng66.shtml

2)TSB to replace a radiator return hose in which may contains a malfunctioning check valve.( but not sure if our a4 have one?)

http://www.dejong947.com/audi/tsb/audi.tb.19-05-02.pdf

hope it helps

[geoshu]

I did change the coolant temperature sensor by the firewall, I used the write-up from a4mods.com.

The second link mentions the car taking long to warm up, mine seems to warm up fine...but I'll double check because the light only turned on a couple days ago.

Another thing, dont know if its related, my a/c never really blew cold, just a bit cool, it seems really weak.