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

Question

My truck is stuck in a severe derate after a long haul through West Virginia. I tried to initiate a parked regen three times but it keeps aborting after 10 minutes with a 'Regen Not Possible' message on the dash. I'm worried the DPF is completely baked or the 7th injector is clogged.

Tom Patel · Accepted Answer

Found the issue was a completely carbon-caked Hydrocarbon Dosier Valve (7th Injector) and a failed DOC. Replaced the Dosier Valve (Part A0004900500) and sent the DPF/DOC out for professional aqueous cleaning as the face of the DOC was plugged with white diesel smoke residue. After reinstalling with new gaskets and torquing the V-bands to 15 Nm, I used DiagnosticLink to perform a Service Regen and 'Reset Ash Accumulation' which cleared the 5MPH derate immediately.

garagegrease · Answer

You need to look at the SCR Inlet Temperature during the first 10 minutes. If it isn't hitting at least 500-600 degrees, your Hydrocarbon (7th) Injector is likely plugged or the fuel line to it is restricted.

road_rambler · Answer

Check your Delta P sensor readings and the tubes leading to it. If those tubes are soot-clogged or leaking moisture, the MCM can't accurately track the pressure drop across the DPF bricks and will kick you out of the regen for safety.

wrenchqueen · Answer

Check your coolant temp. If the engine isn't reaching at least 170F, the MCM won't allow the regen to continue. A stuck-open thermostat is a common silent killer for regen cycles on the DD15 engine platform.

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

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