this has happened to 10+ people this week i think - its the cold weather. Some of us (me included) have booked the car into SEAT to get it looked at (hell thats what a warranty is for) and mine specifically has been diagnosed as coolant temp sensor (AGAIN - already been replaced once this year) but they need to check it over.
If you check your coolant level and all is ok and it beeps, once the car has warmed up I stop the engine and restart, and the
problem doesnt reappear until the car has been sitting overnight again.
Bad design in my opinion - or a very particular component that cannot take the extreme weather it should be able to handle.
The cold weather has also shown problems in my boot doorhandle/lock (again) and now some creaking rear suspension - perhaps these cars should only be used in the sahara?