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

Question

My truck went into a severe derate after a stop for fuel and now I cannot complete a parked regen. It starts the process, gets up to temperature, but then cuts out after 10 minutes with a high soot load error still active. I am worried the DPF is completely face-plugged and I am losing money sitting at this truck stop.

Rachel Nguyen · Accepted Answer

Final solution was replacing the DPF filters and the Hydrocarbon Doser (A0001401539). The DPFs were 95% restricted and could not be cleaned by the machine. I also found the DOC face was slightly heat-damaged. Total cost for two reman DPFs and the doser was about $4,200 plus labor, but it cleared the SPN 5246 FMI 0 derate immediately after a successful service regen.

Kevin Tran · Answer

Check your Delta P sensor readings while the engine is idling. If the pressure differential is too high before the regen even starts, the MCM will abort the bypass to prevent a thermal event in the DPF canister.

garagegrease · Answer

Standard procedure for a failed regen on these GH17 motors is to run an Intake Throttle Valve test using Detroit Assurance/DiagnosticLink. If that valve is sticking, you won't get the airflow restriction needed to build heat.

torque_terry · Answer

You need to look at the Hydrocarbon (HC) doser. If the doser block is leaking or the 7th injector isn't atomizing the fuel correctly, you won't get the DOC inlet temps high enough to actually burn the soot out.

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

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