Derate to 5mph crisis - regen not clearing codes for some reason

A sticky valve can cause erratic results on the relative compression test. How long has it been since you ran the overhead?

 

Just have the dealer try to fix it. Once you have 4 codes, it’s going to be tough to try to fix it yourself. I have the Detroit repair instructions, but they contain a lot of technical terms. Take it to a dealer in a large city where they have a lot of technicians. Someone there is going to know how to solve it.

 

Hi,

I did valve adjustment first and after a month Freightliner did the cylinder compression check.

 

Thanks for the suggestion! Will take it to bigger dealer

 

Above codes coming and going off, but
Yesterday i had new code came up
spn 3720, fmi 15.

Took the truck to my mechanic, said dpf filter full. Based on the above old symptoms, he said better change 1box iso putting new dpf filter. However, he said take it to the dealer and get the 6 fuel injectors checked first b4 putting new 1box.

 

That is the code indicating that the DPFs are full.