RGW

I have a '03 A6 4.2 with about 75K on the clock. It seems to be running just fine but I notice now that the engine temp gauge always reads cold. It used to ramp up quickly in the morning to the middle of the gauge and stay there but now it is stuck on 'C' all the time.

Wondering if this is a gauge problem or a sensor problem?

Should I get it fixed ASAP or is it OK to let it go for a while since the engine appears to be operating normally?

Harleyguy

First get a fault code reading using a VAG/COM device. If it turns out to be the instrument cluster that is acting up, contact Module Masters. There are treads on here describing how to remove the cluster. If you go to Module Masters web site they have instructions on removal. Basically a panel on the dash pulls off and then two screws and you have it out. Very simple and takes about ten minutes. Module masters is very inexpensive and depending on their work load very quick. About a week after I pulled mine I had it back in and working. They also guarantee their work. And no, I don't work for them. First though find out if it's the instrument panel or the sensor/ sending unit. If it isn't overheating then probably no need to panic. Do you get heat from the climate control system? My car is an '04 with the same motor but double the mileage.

tester123

Harleyguy provided great info for the instrument cluster and that could be handy.

Definitely try to pull codes and see if anything shows there. And, I'd add that the funny thing is that the temp sensor is a very cheap item to replace. Actually, I think it may be one of the parts on Audi that doesn't cost much (pretty much everything else is not so kind to the wallet). It should be less than $25 (check ecstuning.com etc.).

Personally, I'd check to see if the connector to the sensor is loose/disconnected and find the actual problem area before replacing parts. But with a sensor so cheap, @75k miles I'd replace it for peace of mind and see if the problem goes away.