Ford Repair: Heat gauge 2009 F150, 5.4 engine, coolant level, engine heat

Question
Heat gauge works now and then.  At times needle drops to 0.  Picture of engine on dash comes on and goes off now and then.

Answer
few questions, first i need to which area of the u.s. you live in, second. i assume you've checked the coolant level ?? also- do happen to have a friend with a scan tool ?? if so, have them scan it when the light is on and get back to with a code. this is not a common concern but would very much like to help.. take care   -b-