2018 Freightliner Cascadia DD15 - Forced Regen Fails and Stuck in 5MPH Derate

Question

My DD15 is stuck in a severe derate and I cannot get a parked regen to complete. It starts the cycle but drops out after about 10 minutes with a high soot load message still active on the dash. I'm worried the DPF is completely face-plugged or there is a sensor issue stopping the process.

Brian O'Connor · Accepted Answer

The issue was a completely clogged Hydrocarbon (HC) Doser valve (Part# A0004900500). I removed the doser and found it was carboned over, preventing fuel from misting into the oxidation catalyst to create the heat needed for regen. After replacing the doser valve and performing a 'DPF Ash Accumulation' reset via DiagnosticLink, the truck completed a full 45-minute parked regen and the 5MPH derate cleared. Total cost for the valve was about $420 plus two hours of labor.

Sam Holloway · Answer

Have you checked your Delta P sensor readings? If the pressure differential sensor is sending erratic data, the MCM will abort the regen to prevent a thermal event in the DPF canister.

Lina Brooks · Answer

You need to look at the DOC inlet temperatures during the first phase of the regen. If you aren't hitting at least 500-600 degrees F quickly, the 7th injector (Hydrocarbon doser) might be clogged or the fuel line to it is pinched.

Marcus Bell · Answer

Check your coolant temps too. If the thermostat is stuck open and the engine isn't reaching at least 170 degrees F, the computer will often cancel the parked regen for safety reasons.

2018 Freightliner Cascadia DD15 - Forced Regen Fails and Stuck in 5MPH Derate

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