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

Question

Running into a wall with this 2018 Cascadia. The truck keeps throwing a soot level high warning and drops into derate. Every time I try to run a parked regen, it starts up fine, but then about 10 minutes in, it just kicks out and says 'Regen Aborted - Low Exhaust Temperature.'

I've checked the intake throttles and they seem to be moving, but the DOC inlet temp just isn't climbing high enough to sustain the burn. My boss thinks it's a plugged DPF face, but I'm not seeing crazy high backpressure until it starts loading up with soot from the failed cycles.

HighwayHelen · Accepted Answer

✅ Confirmed fix: The issue was a completely clogged Hydrocarbon Doser fuel line and a failed Doser Block solenoid. Even though the software was commanding the injection, no fuel was actually reaching the exhaust stream to ignite. Replaced the Doser Valve and the supply line, ran a parked regen, and temps hit 1100F easily. Soot level is back to zero.

ChevyChuck · Answer

Check your Hydrocarbon (HC) doser injector. If the seventh injector is carboned up or the fuel block is restricted, you won't get the fuel spray needed to spike the DOC temps. Pull the doser and run a quantity test into a beaker using DiagnosticLink.

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

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