I have a 2017 F150 eco boost. When towing any trailer and running in tow/haul, sport or regular when the transmission shifts to 9th gear at about 65 mph not long there after a digital readout will come up over the temperature gauge that will go from 226*-232* back and forth, however, no lights come on and the temperature gauge never moves from where it runs normally. I’ve ran it with the digital readout showing for 20-25 miles and nothing runs different. Any idea what may be causing it. It has also done it without a trailer while running 75mph and same thing... no lights come on and temperature gauge doesn’t move.

 

Drop it to 7th, and slow down a bit.
you have to keep the engine running a bit faster to pull off the heat.
Here in Az I've done this on all my trucks and never had an issue.

 

Never had any issues towing until recently. I’ve towed a Malibu ski boat plenty of times with no issue. It will do it with a 5x10 trailer with a four wheeler on it.
it will never run hot in 8th gear

 

Ive seen a rash of failed radiators lately around here. check the temperature difference between inlet and outlet connections to the radiator and see what you get. I dont recall the proper differential, but im sure a quick search can get that number for you.

 

Um, I think the digital reading above the temp gauge is indicating the cylinder head temperature (CHT). In my 2017 5.0 there is no coolant sensor and the gauge reading is derived from this sensor. In ForScan I’ve enable the digital reading to be on all the time and I see readings of 198F to 230F depending on my driving conditions. The coolant gauge always indicates a little less than midway – my normal.
Anyway, I think it’s normal for the cylinder head temperature to run hotter than the actual coolant temperature. I don’t know what the significance of the digital reading appearing on the ECO Boost under certain conditions means?
For an ECO Boost 3.5 running at 55mph according to the Ford the normal CHT sensor reading is 213.8F. Since you’re working it more I would expect this value to go up.

 

So it’s had a new radiator, water pump, new coolant with system flushed prior and thermostat. No help at all. If I could keep it in 8th gear it will never show the digital readout over temp gauge. When it’s reading 230* in 9th gear and you make it go back into 8th gear the digital readout instantly goes away.

 

duh... do you think it goes away because its cooler?