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

Question

I am out on the road and my truck is stuck in a 5mph derate after multiple failed parked regens. The dashboard says service now and the DPF soot level is showing high even though I just tried to burn it out. It starts for a few minutes then the RPMs drop and it cuts back to idle power.

hd_trucker_77 · Accepted Answer

The issue was a completely carbon-plugged Hydrocarbon Doser (A0004900500). I pulled the doser valve and found it built up with coke. After replacing the doser valve (about $450) and performing a 'DPF Ash Accumulator Reset' and 'SCR ADS Self-Check' using Detroit Diagnostic Link, I was able to force a full regen. The truck successfully completed the 45-minute cycle and the 5mph derate cleared immediately.

torque_terry · Answer

Listen for any air leaks near the turbo or the EGR valve. If the engine can't control the boost and EGR flow precisely, it won't reach the thermal management goals required to oxidize the soot in the canisters.

backyard_bart · Answer

You need to check your Delta P sensor readings on the DPF. If the pressure tubes are clogged with soot or if the sensor is biased, the MCM won't allow the regen to complete because it thinks the filter is face-plugged.

Sam Holloway · Answer

Check the DOC inlet temperature during the start of the regen process. If you aren't hitting at least 500 degrees Fahrenheit within the first 10 minutes, your hydrocarbon doser (7th injector) is probably clogged or the fuel block fuse is blown.

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

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