Recently, I've been getting the 'STOP' warning flashing with the water icon lit up on my 2001 307 HDi. And on the display above the radio it also says coolant level is low and needs filling up. Thing is, it's wrong as there's always enough coolant and the gauge never goes to overheating. When I've gone to top it up, I can see plenty of water. So I pour some more water in right to the top and the messages disappear. Topped it up again this morning right to the top, the message disappeared but this time, it came back. So whatever controls the messages is playing up or being oversensitive. I'm going to take the car to an auto electrician but any idea what might cause this?