i have an 08 f550. when towing a load, the temp guage pegs hot and odometer display says reduced engine power and truck won't go over 20mph on the highway. this is random and only happens with a load. it doesn't actually overheat but the guage pegs to hot. any help would be greatly appreciated, since the dealer says it's fine with no codes. thank you.

 

i am not sure but i think you need to check your temp sensor and from what you are talking about it is tied into derating your power when the temperature is high according to your sensor or sender anyway after the story is done thats what i would check first and welcome to diesel bombers and if im not sending you down the right road maybe somebody on here will help out

 

i have found out that the oil temp is getting too high. fan is not coming on so it goes into reduced engine power mode. now just trying to figure out why fan does not come on. the dealer thought i was nuts until a tech rode with me with his computer and witnessed first hand what was happening, only under a heavy load

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the dealer found something wrong with the thermostat, and the fan wouldn't come on. not sure what it was. i didn't get to talk to the tech.

 

Send me the VIN I can send you the warranty history report on it.

 

1FDAF57R78ED55794.. thank you

 

mine did the same twice this week, pegs out on the temp, but is not really overheating, goes into limp home mode, then today it started blowing white smoke, turns out to be unburned fuel, pouring out of exhaust pipe. I think an injector tip must have broken off an filled the cylinder and exhaust with raw fuel. So watch for the white smoke?? Dealer pulling cab in the morning.

 

there was a recall on that (injector tips blowing out) keep us posted on what they find.

 

After 3 days of dignosis....the dealer says this is something new that has never happened before to this engine....... now they say it has/or senses a plugged cat converter or particulant filter. Computer is sensing back pressure causing it to go into the cleaning mode (even though it doesn't show on the dash it is doing it) so it keeps dumping the fuel in to clean the particulant filter?? They are going to change the entire exhaust system and sensors in it.
We shall see, I'll let you know................

 

could end up being the ecm

hope they get you back on the road soon!

 

well now after 9 days of diagnosis........ they decided to replace the engine. just turned over 40K miles.