Stupid red light on temp gauge

[Phoenix]

right the car runs like new, never overheast and is the best lopo i've driven, but what the hell does the red light on the temp gauge mean when it randomly flashes

oh yeh and if you "tap" the top of the dash it goes off

[The G Man]

My Polo was having the same problem - red light kept flickering every now and again - then it would stay on for a few seconds, temperature gauge needle would drop then go back up again followed by more flashing etc etc. If you tapped the top of the dash then the light went out or came on. Very strange...

Anyway, the advice I was given was to replace the temperature guage sender unit (a round thing under the bonnet) So - off I went to the scrappy. Managed to get one (Got the pair just in case I ever needed to replace the other sender as there's two - one blue & one black)

The day I was gonna replace it it rained so I did the job that needed doing on my speedo instead - needed to replace the speedo as i'd put the wrong one in and it was giving me a false speed reading. Whilst I was doing that I noticed that the nuts connecting the temperature gauge unit to the circuitry were very loose and tightened them up with a spanner. Put the new speedo in and now I know what speed I'm doing and the red light/temperature gauge is fine.

So, I reckon this is what the problem is with your car.

[Gareth_GT_Hatch]

loose connection on the gauge sender or header tank level sensor (if it has one?) Could be a fault with the gauge, if, every time it does it, it flashes the same number of times (i e the same number of times it flashes when the ignition is switched on) then its a loose connection somewhere.