X15 Derate

[KenworthRolled]

Morning, I have a 2019 KW with the 605 X15, lately it has been doing a 25% derate and not giving a check engine light or any codes, we bring it back to shop and do a forced regen, then it will be good for the day until it does it again. can anyone point me in the right direction ? its getting pretty old, thanks

[Rawze]

(01-19-2026 )KenworthRolled Wrote:  Morning, I have a 2019 KW with the 605 X15, lately it has been doing a 25% derate and not giving a check engine light or any codes, we bring it back to shop and do a forced regen, then it will be good for the day until it does it again. can anyone point me in the right direction ? its getting pretty old, thanks

find out what the ecm is complaining about during the derate. The fuel control state or cbl fuel state in particular.
info: https://rawze.com/forums/showthread.php?...6#pid28636

it will reveal exactly the circuit in the ecm at any given moment that is in control of the power output, derates (hidden or otherwise) and all.

I would suggest an actual screen recording software like OBS studio to make live video of everything as it changes on the fly, instead of trying to use the spreadsheet recording crap built into CT.