2018 Freightliner Cascadia Derate - SPN 5246 FMI 0 - High Soot Load No Regen

Question

My DD15 is stuck in a 5 MPH derate and won't let me force a parked regen through the dash or my basic scan tool. The soot level is showing 140% and it keeps kicking out halfway through the countdown. I'm sitting at a rest stop trying to avoid a tow to the dealer.

torque_terry · Accepted Answer

The issue was a failed DOC Hydrocarbon Doser (7th injector) and a cracked DPF filter. We replaced the doser valve (part #A0004900500) and sent the DPF for professional cleaning, but it failed the light test and had to be replaced with a re-man unit. Once the new parts were in, we used DiagnosticLink to perform an Aftertreatment Device Replacement reset and a 45-minute parked regen to clear the SPN 5246 derate code. Total cost for parts and labor was $4,200.

Kevin Tran · Answer

Check your DOC inlet temperatures. If you aren't hitting at least 500 degrees within the first few minutes, the Hydrocarbon doser might be failing or the fuel line to the doser is restricted.

shoptech_carlos · Answer

You need to check your Delta P sensor readings. If the sensor is skewed, the MCM won't allow the regen to continue because it thinks the pressure is too high for a safe burn.

Megan Rivera · Answer

Since you are at 140% soot load, you have passed the 'Zone 3' threshold. Standard diagnostic tools won't clear this; you usually need Detroit DiagnosticLink to perform a Service Regen and a forced 'DPF Ash Accumulator Reset' just to trick it into firing.

2018 Freightliner Cascadia Derate - SPN 5246 FMI 0 - High Soot Load No Regen

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