2001 F-350 7.3 Super Duty. 261K miles. New engine at 178K miles. Chipped, but not sure what chip (it was in it when I bought it). I live in Houston and drive to Colorado several times a year. Except for the past couple of years I would get a Service Engine Soon light when climbing up Raton Pass in New Mexico. Once I started down the other side the light would go off and that would be that. I never got the light in any other circumstance. The past couple of years, though, I've been getting the light more and more frequently on this trip. I do not drive the truck much around town in Houston. Mainly to pull my boat to the lake, the 5th wheel to a camping spot, etc. in the winter. Really, the only time I see the SES light is on the trip to Colorado. As I said, the past two years the light has been coming on, and staying on, much more frequently than in the past. It usually will come on when I get into northern Texas where the wind is blowing and it is HOT! The engine temp gauge never moves/overheats but the SES light will come on. This past trip (last week) it stayed on for an hour, maybe a bit longer, each time and was probably on 4 or 5 times throughout the trip. The truck runs fine while it is on. No issues whatsoever but, again, I'm getting worried as it's coming on at times when it did not come on in the past. And it is staying on for much longer periods of time. If we stop and shut the engine down to get gas or what not it is out when I re-start the engine. After some time, again, depending on where I am, etc. it may come back on. I have a feeling it is heat related (once we got to our destination in Colorado the temp was much lower and the light never came on - then again, I was no pulling a load at 70 MPH then either). On that note, I am pulling a small (30') 5th wheel with a utility trailer and 2 motorcycles behind it. All in all I am within the 20K GVWR of the truck.

Any thoughts/ideas? I always, always change the oil/filter with 15 qts of Rotella 15-40 before we head out on this trip. Without exception so I know it has clean, fresh oil. Any guidance/suggestions would be greatly appreciated.

 

I forget what the threshold it but once you go over a certain level of boost it sets the light and it goes off after a fairly short period of time, only to come back on next overboost.

 

Thanks. That helps a lot and makes sense since it does seem to coincide with a downshift/high RPM episode. It does take a while to clear after the RPMs drop back down but given the circumstances (i.e. high winds, some mountain passes, big load, etc.) it's probably bouncing up and down RPM-wise. is there anything I need to be concerned about and/or can or should do to remedy/avoid it?

 

I believe it is 24psi.

The factory MAP sensor is not designed to take much more than the limit so you should probably install something like this:
https://www.riffraffdiesel.com/ocr-o...gulator-99-03/

 

If the SES light comes on you have codes stored. My guess from your description is a P1211. If that's the case, it sounds like tired injector orings to me.