2019 GMC Sierra 3500 HD

Reliability tier: verified - see /disclosure/

Engine: 6.6L Duramax L5P (Duramax, 6.6L)

Denso HP4 common-rail (no CP4 - that was the 2011-2016 LML), BorgWarner VGT turbo with electronic actuator, ceramic-tip glow plugs, in-tank lift pump; Allison 1000 6-speed behind the diesel (context only - engine platform).

Applicable failure modes (10)

• Cooling system wear: water pump, hoses, thermostat (towing duty)
• DEF system failures: tank heater, dosing, quality (L5P)
• DPF ash loading / excessive regeneration + differential pressure sensor
• EGR carbon buildup (valve and intake deposits)
• Fuel contamination damage to the HP4/injector system (no CP4 on the L5P)
• Glow plug failures - fragile ceramic tips (R&R hazard)
• Injector wear / pigtail-connector misfires
• In-tank lift pump / low-pressure fuel delivery stalls
• NOx sensor drift/failure (SCR efficiency codes)
• VGT turbo electronic actuator failure (BorgWarner)

Applicable parts (23)

• Cooling system refill with fresh coolant (service item, all L5P)
• DEF refill - fresh API-certified fluid (service item, all L5P)
• Duramax L5P DEF Dosing Injector, pre-2021 doser (2017-2021) (OEM)
• 6.6L Duramax L5P DPF / SCR aftertreatment assembly - catalog gap
• DPF cleaning service (professional bake-and-blow / thermal regeneration off-truck)
• Duramax L5P DPF Differential Pressure Sensor (OEM)
• Duramax L5P EGR Cooler (OEM)
• Duramax L5P EGR Cooler Bypass Valve (OEM)
• Duramax L5P EGR Valve (OEM)
• Duramax L5P EGT Sensor Position 3 (OEM)
• Duramax L5P Fuel Filter Upgrade Kit, spin-on conversion (Fleece Performance, 2017-2024)
• Duramax L5P Fuel Contamination Repair Kit, 2017-2023 (XDP / Alliant Power)
• Duramax L5P Fuel Filter Service Kit (OEM)
• Duramax L5P Glow Plug (OEM)
• Duramax L5P Glow Plug Control Module (OEM)
• 6.6L Duramax L5P HP4 High-Pressure Fuel Pump (GM 12731367)
• 6.6L Duramax L5P Fuel Injector (GM 12698552, supersedes 12678992/12696966)
• 6.6L Duramax L5P injector seal/connectors - catalog gap
• Duramax L5P Fuel Pump Power Control Module (OEM)
• 6.6L Duramax L5P NOx Sensor, Position 2 / Downstream 2017-2019 (GM 12741484)
• 6.6L Duramax L5P NOx Sensor, Position 1 / Upstream (GM 12718742)
• 6.6L Duramax L5P Thermostat (GM 12680457)
• Duramax L5P Water Pump (OEM)

Platform recipes (3)

• DEF subsystem repair for the L5P (mode fm-l5p-def-system): the emissions DEF hardware fails ahead of the engine - heater elements short or open (the VOQ signal clusters here), tank harnesses chafe, doser injectors crystallize
• Fuel-system health for the L5P (modes fm-l5p-fuel-contamination / fm-l5p-lift-pump): the Denso HP4 does not carry the CP4's catastrophic failure pattern, but it is not contamination-proof - dirty fuel still kills the pump and injectors
• L5P VGT turbo repair (mode fm-l5p-turbo-actuator): the BorgWarner actuator is the most common failure point on the assembly - boost leaks, limp modes and vaned-nozzle position faults

Recalls that include this truck (3)

• 23V-047 (February 2, 2023) - FUEL SYSTEM, DIESEL:STORAGE:TANK ASSEMBLY: General Motors, LLC (GM) is recalling certain 2017-2019 Chevrolet Silverado 2500, 3500, and GMC Sierra 2500, 3500 vehicles equipped with a dual fuel tank option. The rear fuel tank may collapse and prevent the fuel pump...
• 21V-496 (July 1, 2021) - EQUIPMENT:ELECTRICAL:ENGINE BLOCK HEATER: General Motors, LLC (GM) is recalling certain 2017-2019 Chevrolet Silverado 2500, 3500 and 2017-2019 GMC Sierra 2500 and 3500 vehicles equipped with a Duramax diesel 6.6 liter engine and an optional engine-block heater...
• 19V-328 (April 25, 2019) - ENGINE: General Motors LLC (GM) is recalling certain 2019 Chevrolet Silverado 4500, 5500 and 6500 vehicles and 2017-2019 Chevrolet Silverado 2500 and 3500 vehicles and GMC Sierra 2500 and 3500 vehicles equipped with Duramax 6.6...

Matched by the model and model year NHTSA lists for each recall - a recall often covers only part of a year's production, so read its text for the build dates and versions it names. Whether a recall is still open on your VIN is not known here; check nhtsa.gov/recalls. All recalls, investigations and bulletins for this engine: /recalls/duramax-l5p/

Reference for this truck