possible temp sensor issue?

First TDi, do they run below operating temp in cold weather?

Hi, it has defiantly been a while since I was on here. Finally I have gotten a TDi, or rather my girl friend has. She just bought a 2000 Beetle TDi with the 5 speed. we love the car. we love the mileage, first half tank of fuel we got on average 45 mpg! As far as I can tell the car is stock, the guy we bought the car from just had the timing belt replaced along with all the recommended replacement parts including the water pump and the tensioner for the belt. Also while it was in the shop the tech that was working on it changed the timing on the injector pump, so its making more power, at least thats what he said. The only other thing I can tell you about the car right now is that the glow plugs have all been wired together on one circuit. He mentioned that the glow plug light had come on for them to be replaced but they were all checked and fine? so instead of replacing the glow plugs, he wired them together and it get rid of his glow plug light.

My question has to do with the temp light. On the beetle there is a blue temp light that shows until the engine has reached full operating temp(no temp gauge). When it is above 40 degrees F outside the engine will warm up and the light will go out. We just drove the car on a 8hr trip from Detroit to Marquette, MI. When we hit the upper penninsula, after driving for about 5 hrs(light was out), the outside temp dropped to about 40 degrees and the coolant temp light came back on blue. I checked the coolant level and it is actually a little over full. The car runs really well, has no CEL and it doesn't seem to be affecting anything, but I want to be sure that nothing is wrong.

Is the jetta TDi top engine cover different from the beetle engine cover? the car was in a small accident involving a deer and the original cover broke. So he gave us one he had from a jetta, but when I went to put it on last night it seems to be just slightly different. I don't know if I didn't have it in there right or if they actually are different. It appears to be different though.

any ideas?

You should look at a scan guage or vag-com. They will show you what your actual temperatures are. If you do not have one...use the locator to see if someone in your area does.

I do not know about the engine cover...sorry. I would think that if the engine is the same, the cover template would be too.

One word of wisdom...never take your car back to the dealer for service if that is who did the prior work. Spend some time reading...you will see.

You must have been searching. My NB is doing the same thing with the temp light. The temp is fine, i have a scangauge plugged in and most every morning when the temp hits 134-136f the light goes out then when it gets to 154-159f it comes back on. The research i have done so far looks like a bad sensor. TDIparts has them for 15 bucks, but i am going to check the connection on mine and make sure its clean first. The light does not effect anything or throw a code but it is anoying.

Definitely get it fixed, when mine was doing it (no light, but I could watch the gauge go from 190* to 0*) I lost a couple of mpg and started having overboost problems... Have no idea how it had any effect on the overboost.