Hi my 2002 f150 5.4 threw a coolant temp sensor code i replaced that service engine light stayed off about a day came back on with cyclinder head temp senor code heat and going to hot but can take cap off an aint boiling or steaming like its hot an also the oil light is on also couple days ago it was going into limp mode i unpluggeg the engine coolant sensor an it would stop going into limp mode i also installed new thermstat could this be a sensor?or head gasket im lost here ant help thanks

 

I don't know much about this . May be some one here to help you. Bump for your post.

 

Coolant temp sensor/PCM measure coolant temp using a voltage drop value. The Cylinder head measures the temp of the metal itself. So given the 3 indications of over temp,, I'd want to rule it out. Any prior coolant level drop, even needing to add coolant to top off? Any bubbling in the system, or excessive condensation from the pipe? "More so" after a hot soak and a more cold restart condition? Top hose, bottom hose temp,, fairly even on temps checked by hand?

If you have a multi meter, (scan tool that can access PID, even better if you have any access) you can physically check both the voltage and resistance changes at the coolant sensor and get a more 'real time' coolant temp value, or temp indication that the PCM see's. If you have or can pick up an inexpensive radiator thermometer you can get an fairly accurate flow temp indication.

If the coolant temp values 'range' and are within specs per indicated engine running temp/s, then tends to rule out module/hardware failures. Flow, pressures, 'hard part' failures need to be checked as best you can. Pump, radiator core, base engine pieces etc.

A radiator/system pressure tester can help rule out or point to head gasket failures, if severe enough. Generally a larger head gasket issue will cause the system to over pressurize, can bleed coolant back into the bore/s on a hot soak and shows out the pipe, and most often doesn't go unnoticed. Performance, coolant loss, oil contamination, 02's etc.

 

No loss of coolant,not having to add any it had condensation coming out tailpipe but i figured it was from cold temps an pipes warming up,how could you tell if waterpump is gone out?no bubbling in resevoir or pushing coolant back out

 

If a pump or radiator core issue,,

You may be able to manually feel the upper hose, and then the lower. If the lower is noticeably cooler, then the coolant flow may be suspect. Taking in to account thou, the coolant going in to the core will be hotter then the coolant that exits. But if the lower is significantly cooler, or any 'thumping' may point to a flow issue.

Condensation,, normal heating and condensation will generally dissipate, or 'disappear' reasonably quickly after leaving the pipe. Engine coolant when vaporized tends to have a sweet smell, and tends to carry farther through the air colder air..

From what you describe as far as conditions or what you see, doesn't seem to be over temp, but, 3 management indications,,,Hmmm,, As a start, I'd check flow temp 'upper/lower temps by hand as a guesstimate, then with a thermometer or maybe an inexpensive infrared temp gun, if not over temp, a mutil meter check against the coolant temp sensor indication. If it checks, could be connection/module issue

 

Well i sent truck to shop will update when they figure out what the problem is thanks for all the help

 

Great info, thanks for sharing this with us.

 

Update us ASAP..!!

 

Update got truck back from shop apparently autozone sold me bad collant temp sensor causeing send false signal to comp sending engine in limp mode so when it was showing hot it wasnt replaced sensor again everythings fine