I got an audible beep and warning to "STOP", check coolant when I started my car last week. Turned the engine off, checked level, OK. Restarted car again and problem went away. Suspected expansion tank sensor. Took the car to Gilders and they were kind enough to check car and came to the same conclusion. The sensor is prefitted to the tank, so had to order a new one. Quite reasonable at £11. Not fitted yet and I'm still getting the fault, that clears after turning on/off engine. Just wondered if anyone else had the same problem??