According to Au7o's analysis of 2,240+ owner reports, the 2019 GMC Sierra 2500HD has 6 documented known issues, with 5 rated critical. The most serious are CP4.2 High-Pressure Fuel Pump Catastrophic Failure ($8,000-$18,000 repair), Allison 1000/2000 Transmission TCM Failure and Harsh Shifting ($300-$4,500 repair), 6.0L V8 Excessive Oil Consumption and AFM Lifter Wear ($400-$7,000 repair), Rear Fuel Tank Collapse Preventing Fuel Transfer on Diesel Dual-Tank Trucks (Recall 23V047000) ($0-$0 repair) and Roof-Rail Air Bag Inflator End Cap Detachment and Rupture (Multiple NHTSA Recalls) ($0-$0 repair). The most commonly reported issue is CP4.2 High-Pressure Fuel Pump Catastrophic Failure with 920 owner reports. Across all issues with published estimates, repair costs range from $300 to $18,000. DIY maintenance guides at au7o.io.
On the 2011-2020 GMC Sierra 2500HD, the Bosch CP4.2 high-pressure fuel injection pump used on the 2011-2016 LML and 2017-2020 L5P Duramax diesel engines is prone to catastrophic failure that destroys the entire fuel injection system. Unlike its predecessor the CP3, the CP4.2 lacks a roller element and relies solely on fuel for lubrication. When metal fatigue occurs, the pump shatters and sends metal debris throughout the entire high-pressure fuel system — contaminating all six injectors, the fuel rails, return lines, and feed lines. Total repair cost runs $8,000-18,000. A class action lawsuit was filed against GM. The same pump also fails in Ford 6.7 Power Stroke and Ram 6.7 Cummins of the same era.
Replace entire high-pressure fuel system: CP4 pump, all 6 injectors, both fuel rails, return lines, and flush the lift pump/FASS system. Install aftermarket CP3 conversion kit (Fleece FPE-CP3K-LML or FPE-CP3K-L5P) to replace the CP4.2 with the more durable CP3 design. Add a FASS or AirDog lift pump to improve fuel supply. Prevention: never run below 1/4 tank, use quality diesel fuel.
High Confidence920 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
Community reported
430 owners
On the 2014-2020 GMC Sierra 2500HD, the 6.0L L96 V8 gasoline engine in Sierra 2500HD (non-diesel) suffers from Active Fuel Management (AFM) lifter failures similar to the 5.3L in Sierra 1500 — though less frequently due to the higher displacement. More commonly, 6.0L engines exhibit excessive oil consumption (1 qt per 1,000-3,000 miles) from worn valve stem seals and piston rings, particularly between 100,000-150,000 miles. The L96 is a high-output truck engine subjected to heavy towing and payload, which accelerates wear on AFM components.
AFM disabler device (Range Technology RA003B) to prevent lifter wear. Oil consumption: GM oil consumption test procedure — if over 1 qt/2,000 miles, piston ring replacement authorized. Change oil every 5,000 miles with full synthetic Dexos2 5W-30. Valve stem seal replacement for blue smoke on startup.
High Confidence430 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
Community reported
510 owners
On the 2011-2025 GMC Sierra 2500HD, the Allison 1000 (gas) and Allison 2000 (diesel) 6-speed automatic transmissions used in Sierra 2500HD/3500HD are widely regarded as extremely durable, but the Transmission Control Module (TCM) and solenoid pack do develop faults. Common issues include harsh 1-2 shifts, transmission sticking in one gear, slip codes, and the truck going into limp mode (3rd gear only). The Allison's proprietary Transynd fluid is critical — using non-approved fluid is the leading cause of premature solenoid wear. TCM software updates from GM address most calibration-related shift complaints.
Check engine light with transmission codes (P0700, P0730, P0751)
Transmission not shifting above 3rd gear under load
How to Fix
TCM software update at dealer. Allison Transynd fluid service (drain/fill every 30k miles, full exchange every 60k). Solenoid pack replacement (Allison 29539579). TCM replacement if software update fails. Always use genuine Allison Transynd TES-295 or Mobil Delvac 1 ATF — not GM DEXRON products.
High Confidence510 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
On the 2011-2019 GMC Sierra 2500HD, nHTSA campaign 23V047000, opened February 2023, covers Sierra 2500HD diesel trucks in which the rear fuel tank can collapse inward under vacuum because the tank does not vent properly as fuel is drawn out. A collapsed tank stops the transfer pump from moving fuel forward, so the truck can run out of usable fuel while the gauge still shows fuel aboard - and stall in traffic. Related to this same family of complaints, GM had earlier recalled 2011-2012 diesel trucks under 13V615000 for a fuel transfer pump that malfunctions and causes inaccurate fuel gauge readings on the same dual-tank arrangement.
Common Symptoms
Engine stalling or running out of fuel with fuel showing on the gauge
Fuel gauge reading inaccurately
Rear tank visibly deformed or dented inward
Fuel starvation under load
Check engine light with fuel level sensor codes
How to Fix
Free recall remedy under 23V047000: the dealer inspects the rear fuel tank, replaces the tank and/or fuel pump module where it has already deformed, and installs an additional vent hose so the tank can equalize. For the earlier 13V615000 population, dealers inspect and replace the fuel transfer pump at no charge. Verify the VIN on nhtsa.gov/recalls, and do not treat a fuel gauge that reads full while the engine starves as a gauge problem.
On the 2015-2019 GMC Sierra 2500HD, the side-curtain (roof-rail) air bag inflators fitted to GMT900-era and 2015-2019 Sierra 2500HD cabs can have the inflator end cap detach during deployment, releasing compressed gas into the headliner and propelling the cap and headliner components into the occupant compartment. GM has issued a repeating series of NHTSA recalls covering this defect as the affected production population has been refined: 20V736000 and 21V504000 for 2015-era trucks, then 24V756000, 25V432000, 26V166000 and 26V325000 reaching 2018-2019 Sierra 2500HD Crew Cabs. Because a defective inflator can injure the very occupant the bag is meant to protect, NHTSA classes this as a serious safety defect rather than a nuisance.
Common Symptoms
No driver-visible symptom before deployment
Air bag warning lamp in some cases
Recall notice received by mail
How to Fix
Free recall remedy - dealers replace both the left and right roof-rail air bag modules at no charge. Because several overlapping campaigns exist, run the VIN specifically at nhtsa.gov/recalls rather than relying on a single campaign notice: a truck repaired under an earlier campaign may still be open under a later one.
On the 2011-2023 GMC Sierra 2500HD, sierra 2500HD 4WD trucks use a front axle disconnect system with an electronic actuator and Integrated Wheel End (IWE) hubs. The actuator motor and position sensor commonly fail between 80,000-120,000 miles, causing the 4WD system to not engage, to partially engage (binding and vibration), or to throw a 4WD Service warning. Heavy-duty truck use — particularly towing and off-road — accelerates actuator wear. The IWE hubs (vacuum-operated on some variants, electric on others) also fail, causing a grinding or clicking noise from the front axle in 2WD mode when the hub disengages incompletely.
Grinding or clicking from front axle at highway speed in 2WD
Vibration when 4WD engaged on dry pavement
4WD indicator light flashing or not illuminating
Binding or tight steering in 4WD
How to Fix
Replace front axle actuator motor (GM 84243791 or Dorman 600-140). Inspect IWE hubs for wear/failure. Change front differential and transfer case fluid simultaneously. Diagnose with scan tool to confirm actuator vs. TCCM fault. Some owners replace vacuum lines on IWE systems with updated silicone lines to prevent cracking.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
What are the most common GMC Sierra 2500HD problems?
According to Au7o's analysis of 2,240+ owner reports, the 2019 GMC Sierra 2500HD has 6 documented issues. The most frequently reported are: CP4.2 High-Pressure Fuel Pump Catastrophic Failure, Allison 1000/2000 Transmission TCM Failure and Harsh Shifting, 6.0L V8 Excessive Oil Consumption and AFM Lifter Wear. Of these, 5 are rated critical and should be addressed promptly.
Is the GMC Sierra 2500HD reliable?
The 2019 GMC Sierra 2500HD has 6 known issues documented across 2,240+ owner reports. 5 issues are rated critical: CP4.2 High-Pressure Fuel Pump Catastrophic Failure and Allison 1000/2000 Transmission TCM Failure and Harsh Shifting and 6.0L V8 Excessive Oil Consumption and AFM Lifter Wear and Rear Fuel Tank Collapse Preventing Fuel Transfer on Diesel Dual-Tank Trucks (Recall 23V047000) and Roof-Rail Air Bag Inflator End Cap Detachment and Rupture (Multiple NHTSA Recalls). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
How much does it cost to fix common GMC Sierra 2500HD problems?
Repair costs for known GMC Sierra 2500HD issues range from $0 to $18,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, CP4.2 High-Pressure Fuel Pump Catastrophic Failure, typically costs $8,000-$18,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 2011-2020 GMC Sierra 2500HD CP4.2 High-Pressure Fuel Pump Catastrophic Failure?
The Bosch CP4.2 high-pressure fuel injection pump used on the 2011-2016 LML and 2017-2020 L5P Duramax diesel engines is prone to catastrophic failure that destroys the entire fuel injection system. Unlike its predecessor the CP3, the CP4.2 lacks a roller element and relies solely… Repairs typically run $8,000-$18,000. Severity: high.
What is the 2011-2025 GMC Sierra 2500HD Allison 1000/2000 Transmission TCM Failure and Harsh Shifting?
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.
The Allison 1000 (gas) and Allison 2000 (diesel) 6-speed automatic transmissions used in Sierra 2500HD/3500HD are widely regarded as extremely durable, but the Transmission Control Module (TCM) and solenoid pack do develop faults. Common issues include harsh 1-2 shifts, transmiss… Repairs typically run $300-$4,500. Severity: high.
What is the 2014-2020 GMC Sierra 2500HD 6.0L V8 Excessive Oil Consumption and AFM Lifter Wear?
The 6.0L L96 V8 gasoline engine in Sierra 2500HD (non-diesel) suffers from Active Fuel Management (AFM) lifter failures similar to the 5.3L in Sierra 1500 — though less frequently due to the higher displacement. More commonly, 6.0L engines exhibit excessive oil consumption (1 qt… Repairs typically run $400-$7,000. Severity: high.
What is the 2011-2019 GMC Sierra 2500HD Rear Fuel Tank Collapse Preventing Fuel Transfer on Diesel Dual-Tank Trucks (Recall 23V047000)?
NHTSA campaign 23V047000, opened February 2023, covers Sierra 2500HD diesel trucks in which the rear fuel tank can collapse inward under vacuum because the tank does not vent properly as fuel is drawn out. A collapsed tank stops the transfer pump from moving fuel forward, so the… Repairs typically run $0-$0. Severity: high.
What is the 2015-2019 GMC Sierra 2500HD Roof-Rail Air Bag Inflator End Cap Detachment and Rupture (Multiple NHTSA Recalls)?
The side-curtain (roof-rail) air bag inflators fitted to GMT900-era and 2015-2019 Sierra 2500HD cabs can have the inflator end cap detach during deployment, releasing compressed gas into the headliner and propelling the cap and headliner components into the occupant compartment. Repairs typically run $0-$0. Severity: high.
What is the 2011-2023 GMC Sierra 2500HD Front Axle Disconnect Actuator and IWE Hub Failure (4WD Engagement Issues)?
Sierra 2500HD 4WD trucks use a front axle disconnect system with an electronic actuator and Integrated Wheel End (IWE) hubs. The actuator motor and position sensor commonly fail between 80,000-120,000 miles, causing the 4WD system to not engage, to partially engage (binding and v… Repairs typically run $350-$1,800. Severity: medium.
