P2002

P2002 sets when the post-DPF pressure differential and soot model disagree with expected filtration efficiency on Bank 1, meaning the ECM believes the diesel particulate filter is no longer trapping the soot mass it should for the miles and fuel burned. Cheapest-first ladder: scan live data and read DPF differential pressure at idle (should be 0.2 to 0.8 kPa) and under load at 2500 rpm (target 4 to 15 kPa for a partially loaded filter), then check soot load percentage and ash load mileage; if differential is near zero across the load sweep, the DPF substrate is cracked or the pressure tubes are unplugged from the filter, and if soot is above 100 percent the truck never completed an active regen. Next is a bidirectional forced regen, watching EGT 11 climb to 580 to 650 C and post-DPF temp to 600+ C for 20 to 30 minutes while soot load drops below 5 g/L. Caveat: a cracked DPF substrate will pass a forced regen with falling soot but the code returns within 200 miles, so always re-scan after a 100-mile highway loop before condemning the filter.

Vehicle-specific patterns: 2008 to 2010 Ford 6.4L Powerstroke F-250/F-350 crack the DPF substrate from fuel-in-oil dilution and aggressive regen cycles, and Ford TSB 10-23-8 covers updated PCM calibration plus dual radiator inspection; 2007.5 to 2012 Dodge Ram 2500/3500 6.7L Cummins suffer DPF face plugging when owners short-trip the truck and stack interrupted regens, requiring a Cummins INSITE forced regen or thermal bake; 2007 to 2010 GM Duramax LMM Silverado/Sierra 2500 lose differential pressure tubes to soot caking near the EGR cooler, and GM 10-06-04-026 covers tube cleaning before filter replacement; 2011 to 2016 Duramax LML throw P2002 with a stuck-open EGR causing chronic over-fueling, fixed by EGR cleaning before any DPF service. Estimated repair: $180 to $4,200.