Hello, I have searched the forum for my problem and have found some similar
but mine is a little different. Truck has 210K miles, I have had it since 30K. No issues but a radiator change at 130K and two blown plugs/coils. I live in Florida and running the AC all the time an issue developed that the temp gauge pegged instantly at idle while in drive and went into limp mode. Truck was shut down for 5 minutes and then no problems. This has never happened when the truck is moving. If I see the temp gauge start to go up all I have to do is let off the brake and it goes right back to normal. This is very intermittent and may not happen for three or four days at a time. I tried idling with the heat on and Cap off and it did it too. Also at idle with no AC on instead of pegging hot, it pegs cold. Should I try the T-stat first, or is the issue a sensor since it also pegs cold? Any help would be appreciated, as this is my families only vehicle at this time.

 

Sounds like you have an electrical issue not a cooling system issue. Broken wire, bad sensor possibly.
Has it puked any coolant?

 

No coolant leaks.

 

Do you have any codes to read?

 

When I took it to the shop two weeks ago, the mechanic drove it and could not get the problem to duplicate. For what its worth I don't think he had the time. Said there were no codes. I have had a code for Evaporative Emission Control System sensor.

 

Its just really puzzling that when I let off the brake it goes right back to normal.....

 

Then you have a ground in the system somewhere. Maybe a module going bad. I HATE electrical gremlins!


The EECS canister is probably clogged.

 

That figures!! I know nothing about electrical other than changing a light bulb, lol!
Can the canister be unclogged or does it need to be replaced?

 

Ford Truck Enthusiasts Forums - Search Results You will have to read through the posts for a fix. It could be a sensor issue, but this will give you some information on the symptoms and repairs of the system. If you do a search, either forum or site, you can retrieve very valuable info on whatever your issue is. It will require time and reading though.

 

The evap system fault is unrelated to the temperature gauge issue.

 

Glad you pointed that out. I failed to do so. I did the ***.u.me thing!

 

When was the thermostat last changed?

 

A faulty thermostat would never cause that particular symptom, it's an electrical fault in the CHT circuit.