Q5-2011-VA

My emission control check engine light came on and I get P2181 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 gets to the middle, it is always between 1/4 and 1/2, even though the heater works just fine.

Does anyone have instructions on how to replace the thermostat? The part is only $50, but the dealer is asking $800 to install!

It's 2011 Q5, 3.2L engine.

Thanks!

Diogenes

I have the same code and have been researching the issue. As I understand it, the thermostat is located near the bottom of the radiator and to access it you essentially have to go through the same procedure required for the timing belt replacement. There is a lot on the Audi forums regarding the timing belt. Check that and you'll see the issue. If there is an easy way to just replace the thermostat, I haven't found it. I'm still looking

Diogenes

Update: after about a week the CEL went out. Does that mean that the Audi gremlins smiled upon me and I'm out of the woods?

Q5-2011-VA

My CEL also went away after a couple of weeks. The temp gauge also appears to be normal. Hopefully the issue has disappeared for good.

Diogenes

Same here. It has been clear for about two weeks. I'm curious about the coding of the CEL. I would expect that it would be programmed to clear after some interval, even if the underlying condition that triggered it has not been resolved. If it remained illuminated it could not alert you to subsequent faults. It probably pays to get a good OBD II reader or a vag-com.