Welcome to justanswer.
What kind of scan tool did you use to look for codes?
I used the Stealth programmer I used to program my truck. It has dont this before and I used alsao the scanner at advance auto parts . Not the first time this has happened.
Okay does your truck have the allison transmission.
Okay you are going to need to find a shop that can read codes off the transmission control module that is the most common cause of reduced engine power.
It's not the tranny. Why would you think that????
I have had engine power reduced for Fuel filter yet dash would say change fuel filter immedeately. I have had it do it for coolant low. No code or message but added coolant and was ok. Never a tranny issue
Ok when was the last time you changed your fuel filter? You can also get it from the air filter. Usually when I work on these and there is a chip it is from the tranny going into limp mode when you are getting on it.
Fuel filter 3 weeks old and it would say change fuel filter immedeately. Air filter 10 k miles not clogged at all.
Okay do you still have the dpf on your truck
167,000 miles so I guess you never know. Tranny troubles don't show up on code puller? No check engine light either.
Hell no DPF has been gone forver.
Okay and no transmission codes only show up on a scanner like a gm tech2 that most shops have. If the transmission slip at all even if you can't feel it, it will go into limp mode causing reduced engine power so that you don't damage it.
Oh. I hear ya. Well that could be it. At 167 k tranny is old. Makes sense. It will have to be towed. Can't make it up huge hill out of neighbor hood wanted to fix it myself. Thanks!! Got to bite the bullet on this one.
Do I just hit accept to pay you?
Yeah definitely sounds like the tranny. And yes just press accept and positive feedback would be much appreciated. Thank you.