2018 Freightliner Cascadia DD15 - Forced Regen Fails - SPN 3251 FMI 0

Question

Been fighting this DD15 for two days now. The dash shows a high soot load and the 'Regen Required' lamp is solid. I try to initiate a parked regen, and the RPMs climb like normal and it starts building heat, but then it just drops back to idle and throws a 'Regen Aborted' message on the DID.

I hooked up DiagnosticLink and saw the DPF inlet temps aren't getting high enough fast enough. The delta pressure across the DPF seems high, but I can't get the burn to finish to see if it clears. No other active codes besides the soot level and the DPF pressure high.

RamRunnerRay · Accepted Answer

✅ Confirmed fix: The problem was a failed Hydrocarbon Doser fuel line check valve. It was stuck partially open, but not enough to throw a specific fuel pressure code. We replaced the HC doser block and the fuel line. Once replaced, the DOC inlet temps shot up to 600+ degrees during the first 5 minutes of the parked regen and it completed successfully. If that doser isn't spraying a perfect mist, the DOC can't light off.

RoadDawgRicky · Answer

Have you checked the DOC (Diesel Oxidation Catalyst) for face plugging or oil soaking? If the DOC is fouled, it won't be able to generate the exothermic reaction needed to get the DPF hot enough. Take the pipe off the inlet side of the DOC and look for heavy soot or signs of coolant/oil.

2018 Freightliner Cascadia DD15 - Forced Regen Fails - SPN 3251 FMI 0

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