When it was cold the other morning, I switched on the ignition and the coolant warning light was flashing. I checked the coolant level and it was just below the maximum line. The next couple of days the car was fine, but it did it again this morning (cold again), coolant level hasn't changed. The car is running fine.

 

So... Have I got a problem somewhere? Or is the cold messing with the level sensor? It's not something I've ever come across!

Corrosion on the level sensor in the headertank. Can be cleaned up with a toothbrush or a replacement headertank is cheap.

Give the level probes a gentle scrape with the edge of a flat blade screwdriver, sometimes a buildup of gunge on the probe can give a false positive.

Damn - beat me to it

Thanks guys, I'll have a poke around tomorrow...