I own a 2011 f150 5.0. Last summer and now again once this summer I'd have times where driving (already at operating temp) I'd pull into say a drive thru and sit for maybe 5 to 10 minutes after which the Yellow wrench would pop up. Does not effect driving as of yet. Temperatures on the hud only show 197-203 usually less if in motion.

Apparently my wife was driving and same thing happened only after coming home the truck seemingly died or wouldn't accelerate and she had to goto park and restart the truck afterwards it drove fine.

Doesn't leak any fluid and while the temperature reading freaks me out.. It's never been higher or lower since owning. Now living where it gets 85-100 degrees has revealed this problem

Any help I greatly appreciated, using my phone so I apologize for grammar and such

 

Scan the OBD2 for codes.

 

Yes, do as glc said, get the code read.