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

Question

My truck is stuck in a severe derate and I cannot get the parked regen to complete. It starts the process but kicks out after about 10 minutes with a 'Regen Aborted - Low Exhaust Temp' message on the dash. I am worried the 1-box is cooked or the doser is plugged because I can't stay on the road like this.

Jordan Lee · Accepted Answer

The issue was a completely plugged Hydrocarbon Doser Valve (A0004900500). I pulled the doser and the tip was solid carbon. I replaced the doser valve and the fuel line leading to it because it was restricted as well. After clearing the codes with DiagnosticLink and running a service-level forced regen, the temps hit 1100F and the derate cleared. Total cost for parts was about $450 and took 2 hours to swap out.

shoptech_carlos · Answer

Run a relative compression test using DiagnosticLink to make sure you don't have a dead cylinder or a trim issue. If the engine isn't putting out enough heat naturally, the aftertreatment has to work twice as hard and usually fails the cycle.

Megan Rivera · Answer

Look at your seventh injector (hydrocarbon doser). They are notorious for clogging with carbon on the DD15. If the nozzle is carboned over, it won't spray, and your exhaust temps will never reach the 600-800 degree range needed for a successful regen.

Jake Morrison · Answer

Check your Hydrocarbon (HC) doser fuel line. If the line is restricted or the fuel block is gummed up, you won't get enough fuel into the exhaust to raise the temps high enough for the DPF to burn off the soot.

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

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