When I go up steep hills, sometimes mil light engine light and def light come on. After 40 miles, the engine light and def light go off, but mil light stays on. During this time the max boost is only 20 psi. About a day later, the mil light goes off and the boost is up to 30 psi again. Any suggestions?
I’ve encountered the same thing it was a nox sensor that was borderline . It also threw the codes doing a manual burn. My guess is your truck is doing a passive burn and nox isn’t within parameters but after topping hill it falls back into parameters and has a derate until the next time it does a successful burn.. This is what my issue was on a DD15 truck .
I recently had a truck that wouldnt build boost above 20... It ended up getting a new cam and exhaust rockers. But once it started acting up it didnt come and go like yours does. Had to run it like that for 1000 or so miles to get it home to the shop.
It’s a dd15 and it gives me the low nox conversion codes. I’ve replaced both nox sensors and the harness, put in awning kit, replaced filter, pump and doser. Still same problem. This has been happening for a year. I just go up the hills very slow and live with it. Actually, the boost comes back in a few hours, but takes a day for the mil light to go off.
