P2181 - cooling system - thermostat
 

My emission control check engine light came on and I get P 2181 code when I scan it (cooling system problem). I had the same check engine light on 6 months ago and the dealer replaced the Engine Coolant Temp Sensor and reset the light. I suspect the thermostat is stuck open causing the light to come on. The temperature gauge never seems to get to the 1/2 point line, it is always between the 1/4 and 1/2 position, even though the heater works just fine.

Does anyone have instructions on how to replace the thermostat?

I have a 2011 Audi Q5, 3.2L engine.

Thanks!

Was it in fact the thermostat? I have the exact same year Q5 and engine and oddly I get this error code and engine light every season change (Fall and Spring) or drastic temp change. Then it goes away for months at a time.
What was your resolution?

I have an 06 A6 with the 4.2 V8. I am experiencing a similar issue. My temp gauge will quit working. I hook up my scanner and see the P2181 code, I reset the code and the temp gauge starts working again. I do not know if it is the sensor or something deeper. It is odd to me that the gauge quits working until the code is re-set, it works for a few hours then quits again. Any advice?