2018 Freightliner Cascadia SPN 3251 FMI 0 - High DPF Pressure

Question

Running over the road and my 2018 Cascadia keeps asking for a parked regen every 300 miles. Getting a 'high pressure' code for the DPF even right after a manual burn. Losing pulling power on hills and the dash is threatening a 5 mph derate.

I checked the air filter and it's clean. No visible exhaust leaks before the one-box. I'm afraid the DPF is baked but hoping it's just a sensor acting up before I drop $5k on a new aftertreatment stack.

EmissionsEric · Answer

✅ Confirmed fix: Found the issue was the 7th injector (Hydrocarbon Injector) was carboned over and dripping instead of atomizing. It was soaking the face of the DOC, causing it to face-plug and create massive backpressure. Replaced the HC injector and ran a deep service regen to clear it.

NightShiftNate · Answer

Check your Delta P tubes. Those little metal lines running from the DPF to the pressure sensor often get clogged with soot or moisture. If the sensor can't get an accurate reading, it assumes the filter is packed.

2018 Freightliner Cascadia SPN 3251 FMI 0 - High DPF Pressure

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