UK-POLOS.NET - THE VW Polo Forum

2004 1.9 SDI polo, Every so often, when started from cold, theres a Red over heataing light (thermometer over water) flashes continuesly. its done this a few times.
The first time it happened, the car had been idoling for about 5 minutes, i just turned it off, and back on, and the light was out.
Second time it happened, the car was driven untill the coolant temp came up but light was still on, so it was turned off, and started the car again, but light still flashed. A short time later, went back to the car, and the light was out.

So i just went ahead and ordered a new Coolant temp sensor from VW as i heard theyre problematic and Fitted it straight away.

Yesterday morning, again from cold, when the ignition was turned on, the car beeped three times, and the light was flashing again!

As far as i can tell, everythings grand with the car, it doesnt over heat, theres water in the header tank and nothing obvious thats wrong with it. Only thing is i just done a timing belt and water pump and initially put it down to maybe the coolant system still getting rid of any air locks or something, plus there was alot of coolant lost changing the sensor. So im stil hoping it will resolve itself. However, im wondering does anyone else have this problem of heard of it? Do any VAGS use the red over heating light as some sort of Cold warning light even? woud seem a bit odd using a red over heating light lol.

On older cars, and I can only guess that yours is the same, it's the same warning light for coolant level. The float could be sticking, or there could be damp in the connections.

I had this problem with my 02 tdi the red over heating lamp also turns orange to indicate low water level. I replaced the expansion tank but the light still flashed with the 3 beeps when it was started. Turned out to be broken soldered joints on the back of the PCB board on the back of the clocks.