Temp gauge problem

It stopped working and got a replacement from a parts place and now the gauge works fine until it's gets warm (says the gauge) all the pipes are cold engines Luke warm but gauge is going mad and flashing like a perv in a park!

may be incorrect rating part or just cheap rubbish .iot should be a black collar sensor 0-125degree, part number 049919501 or 027919501. try to get genuien if possible, but a struggle theres days. classic-vw.co.uk do them

That's what I've got( 049919501) and I've had it happen befor when I changed the engine and had to put the original one back in as the gauge went mad put now that sensor has had it I've now got the same problem 

check the red/yellow wire carefully, make sure its not shorting out anywhere. might have got damaged during the swap. also make sure the spade connector is clean, and the wire crimp is good

Did you have any luck with this?
Having a similar problem in my Cabrio, light flashes constantly as soon as all the dash light shave switched off.

i have issues as well. it flashes on start up as it should but the temp gauge never moves from the bottom (cold) position. Is this likely to be the little temp sensor or a connection to the clocks? I know the clocks have been changed prior to me owning it.

I re-did the connection to the sensor with a new clip and cleaned the surface of the sensor for a better connection but will replace with a new sensor if this is likely to be the issue? 

It's not the wire it's the sensor given a fause reading I managed to locate a vw one in Cardiff but they won't post it to me and it's like £46 anyway for a £5 sensor I'm just going to put a Vado temp gauge in there as its more accurate

Hoppy if you earth the red/yellow the gauge should go to full, if not its a cluster or wire fault.

mccue yeah genuine sensors are expensive and also nla from vw, try classic-vw.co.uk he has them for cheap. dont think they are genuine but they are good quality

There are still available but couldn't warrant the £46 they wanted

VW in Cardiff has one

Here is a How-to on flaky water temp gauges.
If your water gauge is in-op, but your petrol gauge works see:
Repairing your Flaky Water Temp Gauge | Volkswagen Owners Club Forum

If both your Water temp and Petrol gauge are inop, then it is usually the 10V stabilizer on the back of the speedo.
3 legs, key on, the middle is ground the top 10v the bottom is 12v or battery.