Hello everybody!!!

Can anyone give me advice on the following:

I have an 1999.5 A4 1.8T Quattro. The coolant temp gauge died on me and I replaced the coolant temp sensor but that did not fix the problem... Took it to my mechanic who found a "wire' problem behind the dashboard... He fixed it and showed me the gauge going up to the middle of the scale as the car was running in his shop. Then I drove it on the highway and the gauge dropped all the way down again. I stopped, let the car run for a while and sure enough - the gauge went up again. After I drove it on the highway again for 5-10 minutes it dropped down again!!! Now I don't know if I should trust my mechanic anymore...
Can anyone share a similar experience!
Thank you!
J

 

Did you take it back to your mechanic?

 

No I have not - I wanted to do a little research first...
J

 

Yeah, well, when you are parked and idling, there is no air flow, so the guage is probaly around the middle.

Then you start driving, and the air cools the rad cools the fluid and guage reads lower, because the engine temp is lower.

Whats the problem? Is going all the way down to nothing? How far of a drop? Mine fluctuates some, shouldn't be any problem unless you begin to overheat and run toward the top of the range.

 

I mean it drops down to nothing on the highway - hits rock bottom!
J

 

Still sounds like a coolant temp sensor then. It seems to not be reading correctly.

They are really cheap, like a few dollars, so it might be worth trying a second one. Maybe they never really replaced it the first time around, IDK.