2019 Mack Anthem MP8 - SPN 3251 FMI 0 - DPF Pressure High

Question

My 2019 Anthem is asking for a parked regen every single day now. I'll do the regen, the soot level drops to zero, but within 4-5 hours of driving, it's back up to 80% and the SPN 3251 FMI 0 (DPF Pressure High) kicks in. I'm not seeing any black smoke, and the engine seems to be running smooth otherwise.

I suspect either the DPF is actually cracked/plugged or the differential pressure sensor is lying to the ECM. I checked the tubes for the sensor and they aren't clogged with soot. Mileage is at 450k, and I don't think the filters have ever been professionally cleaned.

MisfireMatt · Accepted Answer

✅ Confirmed fix: Found the 7th injector (hydrocarbon injector) was partially clogged. It was spraying enough fuel to get the DPF hot for a regen, but it wasn't atomizing properly, leading to incomplete 'face cleaning' of the DPF. Replaced the 7th injector and the DPF Seventh Injector Fuel Line. After a deep clean of the DPF, the truck is back to regening once every 4-5 days.

FleetOwnerFiona · Answer

At 450k miles, those DPF filters are likely at their ash limit. A regen only burns off soot, it doesn't remove ash. If the filter is full of ash, there's no volume left for soot, so it fills up almost instantly. You need to pull the cans and send them to a cleaning facility to see if they are still salvageable.

2019 Mack Anthem MP8 - SPN 3251 FMI 0 - DPF Pressure High

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