If the truck made it 38k miles with no problem, it had nothing to do with the OP, especially towing in those hills. The problem is too many sensors and computers, connected with together with too light gauge of wires that tend to break, operating too many low quality mechanical pieces, most likely made in China, that all have to work exactly right at the same time.

I had a DEF level sensor go out at the first of the week. Maximum derate screen came on, red light in the DEF gauge at first was solid, then flashing. Within 30 miles the power was down probably 70%. This was on a Paccar MX13, EPA 2017 series.

All this just for a sending unit. Why not a warning showing the unit was bad and to replace immediately instead of derating. The reason, if the screen told the owner the sending unit was bad, the owner would fix it instead of paying the dealer around $1000.00 to repair it and reset the computer codes.

 

A good while back I noticed my 2011 F350 diesel blowing black smoke a few times. This occurred only after slowing down for a toll booth to 55mph then hard acceleration, temporary loss of power then a lot of black smoke and power return. Took to dealer, no codes but they took it for a drive and was able to replicate. Tech hooked up Laptop and said front and back sensors to DPF filter is outside of parameters. They checked the dpf ceramic filter and it was badly cracked inside and broken into lots of pieces. I believe this was done with a bore scope after removing a sensor. So they asked me if I opened up the exhaust and tried to break it or remove it. I was dumbfounded, truck was still under 40k miles (I believe 33k at the time) and we looked at the exhaust together with tech and Svc Mgr. I pointed to the fact that all the exhausts bolts were severely rusted, including sensors and shows no signs anyone ever touched it after delivery from factory. I was the first owner, biggest mods I have ever done on my 11 super duties I have owned was tinted windows and toolbox. All trucks was brand new purchased, Ford serviced at 5k, only Ford DPF fluids purchased, always all Ford warranties bought.

Ford replaced under warranty at no cost to me and I had the truck back in a few days. I was given a new Ford Expedition to drive for 5 days also at no cost. All new exhausts, sensors etc. Hardware was so badly rusted some things broke just by removing it. Never had another diesel emission problem since on that truck or any other diesel truck.

 

I’m a little late to the party. I found this today but there wasn’t much info. Call your dealer and see if they have any information on this service number. SSM 47321

I found this today but it did not give a service procedure so I don’t know if it’s a ford problem or a you problem.