I have replaced the temp sensor on the lower front grill in front of the radiator and no joy,my symptoms are simple it's a blank display while very ocasionally it will display static so it's not totally dead,actually one time it worked for about two days and dead again.Otherwise the car has been pretty good electronically,radiator fan and that's it.

 

Sounds like it could be a bad circuit display board or wiring harness is pinched some where behind the wheel.

I believe the sensor you replaced does other things too like supplying data to your ECU for cold starts in the morning.

 

Thank you for your reply,when i start it runs about 1200-1400rpm and then settles to normal idle speed after warm up which is probably normal,but i live in a warm place Hot Hot Hot year round.Trying to stay away from the stealer on this one.

 

Our early 2002 Cooper is having the same problem. Display would come and go, but temperature indication was always correct. Finally died completely. Haven't found any good hints on the internet yet, other than a couple of others with the same issue.

Will report back what I find after digging into things.

 

After checking connectors to the tachometer head unit, removed the unit and opened it up. All surface mount component and no easy to spot point of failure or repair.

Bought a used tachometer head off Ebay for around $75. OF course, two days before I swapped, the original one decided to start working again. Decided to go ahead with the swap regardless.

Very quick swap, two torx screws and one plug at the base of the tach head unit. Need to drop the steering wheel to the lowest position to easily access the screws. Then just slip the trim out of the way, unplug the old one and plug in the new one. Having magnetic bits helps with the screw replacement, but can be done without if you have nimble fingers.

Has been close to a month now and the outside temperature display is still functioning normally.

 

Display is still working. So problem in my car was in the tachometer head unit and the used replacement cured it.