2019 GMC Sierra 3500HD Problems: 17 Known Issues

On the 2011-2022 GMC Sierra 3500HD, the variable geometry turbocharger (Garrett GT3788VA on LML, and similar VGT on L5P) used on 6.6L Duramax engines develops carbon buildup on the variable vanes, causing them to stick and resulting in loss of boost control. Owners report surging, lack of power under load, black smoke, and check engine lights. This is a widely documented issue in Duramax owner communities and shops.

On the 2007-2019 GMC Sierra 3500HD Duramax, duramax-equipped Sierra 3500HD owners report hard starting, extended cranking, and rough idle in cold weather due to glow plug system faults. NHTSA complaints and service information commonly involve failed glow plugs, glow plug control module issues, or wiring/connector problems that trigger circuit DTCs and reduce preheat performance.

On the 2011-2020 GMC Sierra 3500HD Duramax, the Duramax diesel Sierra 3500HD (2011+) equipped with the DEF/SCR emission system develops failures in the DEF tank heater, DEF quality sensor, and associated wiring. Wires and connectors at the DEF tank can short or fail, and GM has released DEF tank heater, connector and harness updates for 2020-2021 L5P trucks. Cold weather operation exacerbates DEF system problems because the fluid freezes and depends on the tank heater to thaw.

On the 2008-2019 GMC Sierra 3500HD Duramax, the Allison 1000 transmission paired with the Duramax diesel in Sierra 3500HD trucks has a high failure rate for the Transmission Control Module (TCM). GM issued technician information (PIP4560 series) on Allison TCM parts restrictions. Additional issues include input/output speed sensor failures causing no-forward/reverse conditions, and certain 2012 trucks built with incorrect thrust bearings (GM Customer Satisfaction Program 14043).

On the 2007-2019 GMC Sierra 3500HD, the Allison 1000 automatic transmission paired with Duramax engines in the Sierra 3500HD exhibits torque converter clutch shudder during light throttle cruising between 40–65 MPH as the TCC applies and releases. This is caused by degraded transmission fluid, worn TCC friction material, or contamination in the hydraulic circuit.

On the 2007-2019 GMC Sierra 3500HD, the fully boxed steel frame on 2007–2019 Sierra 3500HD trucks operating in northern and salt-belt states is susceptible to severe corrosion, particularly around crossmember mounting points, rear spring hanger brackets, and fuel/brake line routing areas. GM service bulletin 19-NA-255 covers peeling frame wax coating with visible rust on many 2011–2019 Silverado/Sierra HD frames, which GM attributes to the frame supplier possibly not prepping the frame properly before coating. Frame rust-through can compromise structural integrity and towing safety.

On the 2011-2022 GMC Sierra 3500HD, 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 bulletin 10-06-05-002A explains that if the DPF cleaning message is ignored, DTC P2463 sets, the engine runs in reduced power, and a dealer service regeneration is required.

On the 2015-2023 GMC Sierra 3500HD, sierra 3500HD owners towing heavy loads report intermittent trailer brake output loss, warning messages, or erratic gain behavior from the integrated trailer brake controller. NHTSA complaints and GM service bulletins/diagnostics commonly point to module/software issues, poor connector pin fit/corrosion at the 7-way, or wiring faults that cause the system to disable trailer brakes unexpectedly.

On the 2011-2019 GMC Sierra 3500HD, on Sierra 3500HD trucks equipped with hydroboost, a loss of power steering hydraulic pressure can also reduce brake assist. Owners report a sudden hard brake pedal and increased stopping distance, often accompanied by power steering noise or intermittent steering assist. NHTSA complaints and owner reports commonly tie this to power steering pump wear, hose leaks, or aeration/foaming in the system under load or during low-speed maneuvers.

On the 2015-2024 GMC Sierra 3500HD, the fuel injectors on the Duramax LML (Bosch piezoelectric) and L5P (Denso solenoid) engines can fail due to contaminated fuel, high-mileage wear, or internal electrical faults. A failed injector causes white smoke on startup, rough idle, misfires on the affected cylinder, and fuel dilution of the engine oil. The high fuel rail pressures (about 29,000 PSI on the L5P) stress the injectors over time. Contaminated fuel from bulk diesel stations accelerates injector wear.

On the 2007-2022 GMC Sierra 3500HD, the front axle disconnect actuator (also called the front axle engagement actuator) on four-wheel-drive Sierra 3500HD models is known to fail, preventing proper engagement or disengagement of 4WD. Owners report grinding noises from the front axle area in 2WD mode due to the axle failing to fully disengage, or the inability to engage 4WD when needed. The actuator on these trucks is an electric motor unit on the front axle; failed actuator motors and water intrusion or corrosion at the actuator wiring/connectors are the common root causes.

On the 2011-2019 GMC Sierra 3500HD, owners report gear oil leaks at the rear differential pinion seal, sometimes after towing or sustained highway speeds. NHTSA complaints and owner reports describe oil slinging onto the underbody and a developing howl if fluid level drops. The issue is commonly associated with seal wear, yoke surface wear, or excessive pinion angle/driveline vibration.

On the 2014-2019 GMC Sierra 3500HD, owners commonly report the A/C stops cooling due to refrigerant leaks at the condenser, often from corrosion, stone impacts, or seam leaks. NHTSA complaints and owner forums frequently describe repeated recharges that only temporarily restore cooling. The issue is most often reported on 2014–2019 trucks but also appears on other years depending on condenser design.

On the 2007-2019 GMC Sierra 3500HD, sierra 3500HD owners report clicking/ticking behind the dash and inability to control cabin temperature due to HVAC blend door or mode door actuator failures. Owner reports describe stripped actuator gears or actuator motor failures that can leave the truck stuck on hot, cold, defrost, or a single vent mode.

On the 2011-2024 GMC Sierra 3500HD, the cast iron exhaust manifolds on the Duramax diesel engine are prone to cracking and warping due to extreme exhaust gas temperatures and thermal cycling. Cracks typically develop at the manifold-to-head mounting points, causing exhaust leaks that produce a ticking noise on cold starts. The up-pipe connections also warp, allowing soot to blow onto engine components. This issue affects both the LML (2011-2016) and L5P (2017-2024) engines.

On the 2015-2024 GMC Sierra 3500HD, the recirculating ball steering gear box on the Sierra 3500HD develops fluid leaks at the input shaft seal and sector shaft seal, leading to power steering fluid loss and increased steering play. The heavy-duty application and large tires accelerate wear on the steering box internals. Owners report the steering develops excessive play (1-2 inches at the wheel) and a wandering feeling on the highway, especially when towing.

On the 2015-2020 GMC Sierra 3500HD, the instrument cluster in 2015-2020 Sierra 3500HD trucks suffers from LCD pixel failure, causing portions of the Driver Information Center (DIC) display to become unreadable. Individual pixels or entire segments go blank, making it impossible to read trip computer data, gear indicator, or warning messages. GM bulletins tie blank or inoperative cluster displays to cluster software (PI1318B, reprogramming) and, on 2017 trucks built Oct.-Dec. 2016, to a cluster flash-memory defect (17-NA-218, cluster replacement). The speedometer and tachometer gauges may also develop stepper motor failures, causing inaccurate or stuck readings.