About 2 months ago my temperature gauge occasionally started going nuts when I start my car. It fans back and forth like crazy making a red blur then it'll slow down and jerk around, etc... some times it does it long enough to trip the overheating warning, sometimes not. It always stops and behaves normally after 5 - 10 minutes. The frequency of this has increased so that it now does it 3 out of 4 times I start my car. I live in Alaskaso it's always been cold outside when it's started doing this. And since it stops doing it after5 -10 minutesithas never done it on a longer drive when the engine mighthaveactuallyhad a chance ofoverheating. Anyone seen this before? Ididn't find any posts about it.

The only other thing that seems weird ismy gas gauge reads half full now when there's only 5gallons left in the tank... and it didn't used to do that. Don't know if that could be related or not.

 

Sounds like a bad cluster! Hope it's not like this!

 

I had the exact same problem on my old Corrado. I replaced my temperature gauge after getting the cooling system completely checked out by a pro. After the new temp gauge was in place the problem went away forever. Now assuming my old VW and your new Audi use pretty similar temp gauge technology I would be a bout 95% certain you need a new gauge. You unlikely need a whole new cluster, just the temperature gauge should be fine.

 

Yeah, but his fuel gauge is also giving incorrect information...

 

Check the engine temp using the Climate Control diagnostics first. Set it to channel 49C and see what info you get. If it is still fluctating wildly it may just be the coolant temp sensor.

 

Perhaps both gauges then. ALthough it may be cheaper to just buy a whole new cluster if you can find one at a junk yard. I haven't sorted through the Bentley's but since the fuel and temp gauges are right nest to one another they may use a similar wiring harness. I'm not certain though.

 

Fuel gauge problem, may just be a case of fouled fuel sensors in the tank. You can try running a couple of tanks through with a bottle of Techron in each. It has shown to be effective in removing the sulphur compound build up that is caused by some gasoline blends.

 

It's a bad cluster... about 60% of all Audis have this same problem. My cluster does the exact same thing yours does. I know my tank is empty when my needle is at the half way mark.