P246C on GMC
Diesel Particulate Filter Restriction - Forced Regeneration
P246C on GMC vehicles indicates diesel particulate filter restriction - forced regeneration. Au7o has documented this code across 1 GMC model — most commonly on Sierra 3500HD. This diesel emissions code sets when the engine control module detects that the diesel particulate filter (DPF) is heavily restricted with trapped soot, to the point that normal cleaning cycles have not kept up. The DPF captures soot from the exhaust and periodically burns it off in a process called regeneration; when soot load gets too high, the system flags this code and often calls for a forced regeneration or reduces engine power to protect the filter and engine. It generally indicates the filter is clogged and that something has been preventing successful regeneration. Ignoring it can lead to limited power (limp mode) and eventual filter damage. Typical repair costs on GMC range from $300 to $3,500, depending on the specific model and root cause.
Common Causes of P246C
- •Excessive soot buildup from too many short trips that block regeneration
- •Faulty DPF differential pressure sensor or clogged sensor hoses
- •Failed or incomplete regeneration cycles
- •Faulty exhaust temperature sensor
- •EGR system fault increasing soot production
- •Fuel injector or other engine fault causing heavy soot
- •Physically clogged or aging diesel particulate filter
P246C on GMC by Model
GMC Sierra 3500HD(1 issue)
- DPF (Diesel Particulate Filter) Clogging and Regeneration Failure2011-2022
The Duramax diesel DPF becomes clogged with soot under low-speed, short-trip, or heavy towing duty cycles that prevent complete passive regeneration. Owners report the truck entering limp mode, reduced power, and repeated active regen cycles that fail to fully clean the filter. GM TSB 14-06-04-003 addresses regen strategy calibration updates for LML and L5P engines.
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View P246C across all makes →Frequently Asked Questions
What does P246C mean on GMC?▼
P246C stands for "Diesel Particulate Filter Restriction - Forced Regeneration." This diesel emissions code sets when the engine control module detects that the diesel particulate filter (DPF) is heavily restricted with trapped soot, to the point that normal cleaning cycles have not kept up. The DPF captures soot from the exhaust and periodically burns it off in a process called regeneration; when soot load gets too high, the system flags this code and often calls for a forced regeneration or reduces engine power to protect the filter and engine. It generally indicates the filter is clogged and that something has been preventing successful regeneration. Ignoring it can lead to limited power (limp mode) and eventual filter damage. On GMC specifically, this code is documented across 1 model.
What causes P246C on GMC vehicles?▼
Common causes on GMC: Excessive soot buildup from too many short trips that block regeneration, Faulty DPF differential pressure sensor or clogged sensor hoses, Failed or incomplete regeneration cycles, Faulty exhaust temperature sensor, EGR system fault increasing soot production. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P246C on a GMC?▼
Repair costs on GMC range from $300 to $3,500, depending on the specific model and root cause.
Which GMC models have P246C documented?▼
Au7o has documented P246C on 1 GMC model: Sierra 3500HD.