2019 GMC Sierra 3500 - L5P Duramax P2002 DPF Efficiency Below Threshold

Question

My L5P has been going into regen every 150 miles and finally threw P2002. I usually do a mix of highway and city driving, but I haven't changed my driving habits. The soot level on my iDash jumps from 30% to 100% very quickly.

I suspect a leak in the charge air cooler or a faulty DPF pressure sensor. I've heard the L5P injectors are usually solid, and I don't see any black smoke (obviously, with a DPF). The dealer wants to just replace the DPF for $4,500 but I'm looking for a proper diagnosis.

GrandmaGeartooth · Answer

✅ Confirmed fix: The P2002 was caused by a cracked DPF substrate, which allowed particulate matter to bypass the filter and fouled the downstream sensors. You can verify this by wiping the inside of the tailpipe—if there is any black soot at all, the filter is cracked. Replaced the DPF assembly under the federal emissions warranty (8yr/80k miles) and the regen intervals returned to the normal 500-700 mile range.

MountainMechMo · Answer

Check your differential pressure sensor hoses. On the L5P, these can get soot-clogged or the rubber lines can crack, giving the ECM a false reading of the pressure drop across the DPF. Pull the lines and blow them out with compressed air to see if it changes your pressure readings.

2019 GMC Sierra 3500 - L5P Duramax P2002 DPF Efficiency Below Threshold

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