1.9 tdi temperature gauge

[jsosic]

Hi guys,

I own 1.9tdi bought new in December 2008, with around 60k miles on the clock, mostly highway. Last two years I did around 5k, mostly city driving (cause I now work from home and don't travel as much), and I've noticed one strange issue lately.

Gauge for temperature was always pinned to 90 degrees (vertically) after engine gets warm, and wouldn't move much, but lately, it gets stuck just a millimeter before 90 degrees, stays there, then falls a little bit (maybe a mm or so), then comes back again almost covering the 90 line, but not completely and then drops again.... sometimes it does climb correctly and stays on 90, but there's much more irregularity then before.

I've also noticed 3 weeks ago when I did 300 mile trip on the highway, gauge was at 90 and then slipped a bit all of a sudden.

My impression is that thermostat is probably becoming faulty. What's the risk of it getting stuck in closed position? Should I change it immediately? Or could it be some other problem, like sensor or something.

Thanks.

 

[leshkin]

The dash gauge is dumbed down and will stay on 90 even if you are a bit over or under. It sounds like either your temp sender is foo-bared (reading incorrect temp) or the thermostat is stuck open (allows more coolant to circulate when it shouldn't), which does not allow the car to fully warm up.

I'd get it looked at sooner rather than later - I'm not sure which is easier to do/check first on your engine, but I'd start with the cheaper one first

 

[Ady786]

Are the heaters warm on the car or are they cold

 

[desertstorm]

It will be the coolant temp sensor. Very common problem. If it was thermostat issue the temperature wouldn't vary as much as it does over a few seconds.

 

[vag-tech]

If possible get a look at the temp sensor in live data...even better log over time. It'll be all over the place if defective.

 

[jsosic]

Can I keep laptop with VCDS attached while driving the car, or ?

 

[vag-tech]

Yes....and plot graph.
Set all this up before test drive obviously, observing results only when safe to do so.