2004 Excursion, 158,000 miles, has run great since we got it a few years ago. The other day, my wife was running a bunch of errands, very hot day, black excursion. Not far from home, Excursion went into safe mode. Luckily she wasn't too far from home, so she took the backroads and got her home. I scanned the codes and there were a bunch of codes, which mostly seemed to be related to electrical/sensor issues. The next day, the Excursion ran fine. I went ahead and changed the alternator and cleared the codes, to see what "real" issues would pop back up. The only one that has come back is P1299, the Cylinder Over-temperature protection system active code...however, we've driven her over 300 miles with no overheating or driving issues. The only thing I have noticed was after church Sunday when we stopped after driving for a while, my wife and son got out to do something, and I was sitting in the running Excursion with the other boys. The temperature gauge started to creep up, then went hot. I shut it off and we waited a while. When we were done and restarted, gauge was normal and ran fine. Later in the day, it did the same thing when we stopped somewhere else, but this time I just watched and didn't shut it off. The gauge went high, but then went right back to normal. I'm thinking thermostat is intermittently getting stuck and this is what initially caused the over-temp condition.


I've ordered a new thermostat and o-ring and will replace that and put in new coolant (coolant level is normal and has never been low), probably needs to be done anyway. Is there any likelihood that this is a sensor issue and the sensor needs to be replaced as well? Family is getting ready to go on a 700 mile trip in a few weeks, and I don't want this to cause any issues on the drive, so I want to solve the issue quickly.
Thanks for your help.

 

I assume gas engine? You might try because it is cheap.

Do you have a SG2 so you can monitor what the coolant temperature actually is, rather than going by the gauge?

When you flush the coolant, make sure you run lots of distilled water through it to really clean it out. I would run two bottles of flush additive through it also.




Image should point you in the right direction for the sensor, assuming you have a V10.

 

Thanks, the diagram is helpful. Yes, V-10 gas, sorry I should have included that very important information. I do have a Lemur Blue Driver Bluetooth scanner and when I was monitoring coolant temperature it was running normal at 190F...but that wasn't when I saw the gauge jump up and back down. Will probably just go ahead and replace the sensor too. Thank you.

 

Did some looking around the engine last night and looking through the shop manual. It's a little buried, shop manual says to take off the upper intake manifold to replace the sensor. Anybody know if it can be done without taking off too much stuff? Looks like you might be able to get to it by moving the alternator, if you use some long reach tools, and a bit of contortion??

 

Replaced the CHT sensor this weekend, along with a coolant flush and thermostat replacement. You can indeed get to the cylinder head temperature sensor just by removing the alternator, without removing the manifold. It's a tight space, but can be done. A stubby 3/4" wrench would probably be helpful, but I was able to accomplish it with a regular wrench. Make sure you're wrenching on the sensor body, and not on the plastic plug, which will twist off very easily...Luckily I only did that with the sensor I was removing!

 

Good to hear. Put some miles on her now and report back if the code is gone for good.

 

Any update as to the problem has been resolved? I am having the exact same issue right now and tried all of these steps already. Hoping to find more insight in to the issue with others...

 

Do you have a OBD2 gauge to read actual coolant temp?
Possible causes could be water pump, tstat, sensor, radiator - lots of debris on front, kinked hose, etc.
driving or stopped idling?
you should start your own thread with the history/what you already tried and your original symptoms!

 

Problem seems to have been resolved for me. Code has not reappeared, and has been driven 1,000 miles with no overheat issues or check engine light.

 

Here’s a quick video that hopefully helps others out. 2016 F-150 2.7