SkodaMark2

Just as a quick update for those interested - I attached an ODB2 reader to my car to check what was triggering the coolant light each time and it turned out the car was actually getting very hot (~130 degC), so not just the bottle sensor on this occasion. This was diagnosed as the thermostat sticking so not allowing the coolant to circulate - I've now had this swapped out and the car seems to be running much better. Thanks everyone for their help too.

Thanks for the advice, the metal prongs don't seem to be accessible in the expansion bottle so I'll look at getting it replaced.

Recently I've been experiencing an intermittent fault with the cooling system on my car (a 1.2 TSI Fabia) where the red coolant light starts flashing and a warning buzzer sounds when I'm driving. When I pull over and restart the engine the warning light goes out immediately and the car always has plenty of coolant and doesn't show any other visible issues or signs of overheating. I've been led to believe that the flashing nature of this light means that this is likely a sensor fault or an incorrect low coolant warning rather than an overheating issue (but maybe someone could confirm?). Notably I never have any issue on short journeys (<15 minutes) and almost always just about 15 - 30 minutes in, normally shortly after joining a motorway or similar - so realistically just when the engine would be approaching its full operating temperature. This suggests to me that it may be temperature related - if not overheating then something triggered by the engine warming up. Generally once restarted the fault won't reoccur for the rest of the journey and I can sometimes go several long journeys (200 miles +) before I experience the issue again. I have been to a garage previously and they did replace a coolant sensor that they suspected of being at issue (they unfortunately couldn't reproduce the fault in the garage, only review the sensor data). This did appear to fix the issue for several months but it has now returned (possibly a new fault or just chance that it worked again for the last few months). Does anyone have any suggestions as to what the most likely cause is and if there's any straight forward way of telling what fault caused the warning light (overheating, temperature sensor fault, coolant level sensor etc.)? My car doesn't have a temperature gauge unfortunately but I am planning on getting an ECU reader so I can at least see what values are being reported when the warning light is triggered. Thanks in advance for any help you can offer.