My daughter has just purchased a Ford KA 06. After travelling 10 miles with the heater on cold the engine overheating warning light comes on and we had the coolant bubbling and steam coming out. This has happened twice now and the only way to stop this is to have the heater on full heat and the windows open. The car has done 26k miles. Any help with possible causes would be appreciated. By the way I know very little about cars but any pointers would help because I will be seeing a mechanic tomorrow.

sounds like the thermostat has gone .

a cheap and easy job to diy.

if it's not that then i would guess it's a dodgy sender unit or similar

Head gasket failure is quite common on the rocam unit, our dealership has done several.

Thanks for the replies.

The car has overheated again today but as soon as we turn the heater to hot the temperature warning light goes off and the coolant begins to cool. We have replaced the coolant cap thinking that may be faulty but that has made no difference. Have bled the system and there's no air present.

Thermostat replaced and fingers crossed the problem has gone away - thanks for the advice.