over the past few weeks ive noticed that especially when very cold, if i start the engine in the morning and let it idle for 20-30 secs before driving I get a coolant light flash and beep.

If i drive off immediately it doesn't come on and once its on the only way it goes out is if I restart the engine

The coolant levels are fine and engine doesn't overheat so I am right in thinking the coolant temp sensor may be on its way out?

I think the flash and beep means coolant shortage (erroneously in your case) rather than a temperature problem, but if you can get VCDS plugged into the car you could examine reported coolant temperatures at ambient and fully warmed up conditions and assess plausibility. If the numbers look reasonable, you can probably conclude that the coolant temperature sensor is OK, especially if your coolant temp gauge behaves reasonably, rising to 90 after a mile or two/three and staying there?

 

Quite often, it seems that replacing the expansion tank fixes these spurious low-coolant warnings, genuine Skoda ones aren't a king's ransom to acquire.

I have to admit though that the one time I've tried to fix this, this way, for a workmate, it didn't work.  I think it must be an instrument cluster problem in his, but he's not sufficiently bothered by it to dig deeper.

Edited 18 November, 20169 yr by Wino

I reckon it is a problem with the level thing in the tank judging by what else ive seen on the forums. As soon as the car is moved the light wont come on (if that makes sense).

Only if you start it and idle without moving the light comes on

I dont know how the level sensor works inside the expansion tank however It would seem logical if its some kind of float or something that may be intermittent, and when disturbed (through movement of coolant when moving vehicle) it works again

 

The engine temp gauge goes up to 90 degrees as it should and never moves from there no matter how hard you drive the car. Only issue i have with the engine is that the idle is a bit rough when cold and sometimes wants to stall if you lift off throttle when first started

might be worth replacing tank for the sake of £13 and seeing what happens

I dont know how the level sensor works inside the expansion tank however It would seem logical if its some kind of float or something that may be intermittent, and when disturbed (through movement of coolant when moving vehicle) it works again

 

 

It's just two metal prongs and works by resistance. The prongs can get contaminated and you can't reach inside to clean them because of the design of the expansion bottle neck. A new expansion bottle is pretty cheap, though. I fitted one to mine as a matter of course when I got the car and have had no issues.