I normally drive to work and back everyday and have no problems with the cooling fan switching off with the engine, however if I stop for 10 minutes to got to the shop and then drive home (a 5 minute drive) the cooling fan stays on after I switch the engine off. Even after 10 minutes the fan is still on. If I switch the engine on and then off the fan stops. Coolant level is fine, there are no leaks and temp gauge sits in normal position (middle of gauge). Is there something wrong with the cooling sensors?