Well, it happened to me. I was 2 hours into my trip and towing the camper when I got the reduced power CEL. I have 28,000 miles on my truck and always tow in "tow/haul" mode with the exhaust brake on. I was lucky in that I has on a limited access highway and just happened to be approaching an exit to a fuel station with big rig access. I limped in there at about 20MPH checked the code with my Forscan lite and found the P259F code. I typed that into Google and found a thread on another Diesel forum! Some guys said it went away after 3 or 4 restartes. So, I tried a couple of restarts...no luck. I was down to half a tank of fuel so I filled up and parked. As long as I was parked, I went into the camper and used the bathroom. When I got back in the truck, I thought about the WiFi scan adapter plugged into my OBDII connector and wondered if I should unplug it. I did and everything worked! So, I drove the next 4 hours in "tow/haul" mode, but I left the EB off. I also never plugged in the WiFi scan adapter because I didn't want to risk going into the reduced power mode again. Anyway, we made it home without incident. One of the reasons I traded my 2013 in on a 2015 was to get the engine improvements and the EB. I sure don't want to give up the EB. I'm going to take mine to the dealer, but after reading this post, I'm not expecting anything much. Anyone have any information, ideas or solutions on this?

 

I only turn on the Engine Brake when I need it such as in the mountains. Otherwise I leave it off.

According to the code, the PCM thought you had over boosted the turbo or so it appears.

For the pickup applications, use of the engine brake function can result in conditions where a momentary slow
response of the turbocharger vanes to movement can result in a transient high pressure condition that can be
erroneously detected as overboost by the pressure based monitor. Instead, a monitor of exhaust pressure above
a maximum threshold is used as the threshold overboost monitor.

 

But, what does that mean? How is it fixed?

 

There is no fix if there is no real problem except not use EB all the time.

I think your fix is to leave the EB off unless you are in mountains and traveling at speeds less than 50mph while towing.

 

That ain't no fun! I like the way it slows me down and saves brakes. I only use it when towing and you would think it could handle it. Color me disappointed. Thanks for the info.

 

theres a programming update for that code in the 2015/2016 trucks.

 

Thanks Diesel tech!

 

Anyone have any additional information on the programming update to solve this? I just had this code trigger on Saturday, towing back from up north. I was getting into the throttle uphill and the code threw and "reduced engine power" came up. Dealer checked and confirmed the code (was stored, CEL was off), but told me I'm all set. I don't feel "all set."

 

My 2015 did the same thing last August. Was pulling a load of horses up over Malad Pass on I-15. It was 100° and long steep climb. Almost at the summit, my truck shut down. I coasted to the side, Pulled the codes with my Edge CTS and called the Ford dealer. Gave them code and they told me it was Turbo Overboost. I cleared the codes and the truck started right up and we continued on our trip.

When I got home, Took truck in and they reflashed it to correct the programming. No problems after that.

 

Thanks. I have no way of knowing what version my PCM software is, vs when this fix was introduced.

 

I had not heard of it till my truck threw the code in August.

When I called the service write while sitting on the side of the hiway, She acted like it was known problem and not a big deal. I told her I had a Edge CTS that could read and clear codes. She told me to go ahead and clear it and try restarting the engine.

My engine started right up after clearing the code and I ran pretty hard for the next 4 days hauling horses to and from Yellowstone area. A week later I got in and had them reflash it. They wanted to charge me for the reflash, and I reminded them of the code and failure. She checked in the system and came back and waived all fees saying it was a covered warranty issue.

 

Mine did it this summer and after about the 3rd or 4th attempt, it started and the code was cleared. When I got home, the dealer did the reflash and it has been good ever since.

 

Thanks. Do you know if you were already on the latest? He said he just reflashed mine again, and I was at latest, but that he upgraded all other modules too.

 

Mine was not at the latest revision.

 

And I have no idea if mine was either, just what I was told. He was convinced that a flash/upgrade wouldn't solve this but to his credit, he did it anyway for me. Is there any way to see your software version without a code reader and the software?