strange idle, shaking, and temp guage readings

[#2isgreen]

This is not a new problem but its been getting worse so time to deal with it...

CEL is on. Vag-com reads code as "low voltage condition at engine coolant sensor".

The dash temp gauge needle swings from center, to 0, all the time as if its losing signal or ground or something.
When the gauge is reading 0 I think the engine is going into a warming cycle cause it thinks its cold and the rpm's rise to 1100-1200. And the cooling fan engages.

on top of all that, if everything happens to be functioning properly, the engine will shake the whole car at stopped idle. Normal idle rpm, no fan, seems weird.

Any ideas?

 

[Sella Turcica]

year?

 

[#2isgreen]

2006 i'm having trouble getting my sig to come up in my posts, any suggestions for that too?

 

[#2isgreen]

well i guess i figured that one out...

 

[#2isgreen]

I put a new coolant temp sensor in it a few months ago, which didn't make a difference. Last night I put the origional back in just out of curiosity and now the guage is worse, only reads the temp maybe 50% of the time. Are these sensors known to be hit or miss? Should I try a 3rd?

 

[#2isgreen]

No ideas?

 

[AD5GB]

I'm not a VW mechanic so I only see one TDi. (mine) I've not experienced the problem nor have I heard of it on these forums. If it were me I'd be inclined to do a VCDS scan and start looking at harnesses, connections and the like, and go from there.

 

[Sella Turcica]

I used to have an old BMW M3 that did the funky-coolant-temp-gauge dance. Turned out that it was a bad connection at the connector from a wiring harness to the sensor itself in the cylinder head. Maybe spray it out with connection cleaner?