Tow/haul button and check engine light

[Jbt816]

removing thread as it was in the wrong location

 

[Drewster]

Yeah, the Check Engine Light and different driving probably means you're getting forced into open loop or some other mode to protect the engine - I doubt it has anything to do with Tow/ Haul.

I'm guessing the truck is out of warranty since it's used? If so, I would try replacing the bank 2 O2 sensor (Get the actual OE/ OEM replacement and not the wire-it-yourself BS) and check for any leaks, cracked manifolds, etc. If it still pops up I would probably replace the injectors on that bank.

 

[Quint]

My 2015 occasionally threw a code (check engine light) but only when I would tow. The code was for a misfire on Cylinder #5. Eventually I learned that this was an early warning to the cam & lifter failure. My shop originally replaced the #5 plugs, cap, and wires but eventually realized it was something deeper.

Good luck