The 2020-2026 model years mark the fourth generation for the Sierra 2500 as the brand’s heavy duty pickup truck. Known for its versatility and luxury interior, the Sierra three-quarter ton is a favorite among HD truck buyers, but is not without some known problems.
The following information comes from the National Highway Traffic Safety Administration (NHTSA), GMC news releases, user/owner/technician forums such as GM-Trucks.com, and Facebook owner’s groups.
Sierra 2500 Engine & Transmission Issues
These issues are a combination of NHTSA and TSBs related to engine and transmission problems for the Sierra 2500 HD. Reference numbers for each are given in parentheses. The Sierra 2500 has two engines: a 6.6L gasoline V8 and one 6.6L Duramax diesel.
Rear-Wheel Lockup From Failed Transmission Valve (24V-797 and 26V-083): This recall affects certain 2020 Sierra 2500 HD trucks equipped with the Duramax diesel engine. Excessive wear in a transmission control valve could cause harsh shifting and, in rare cases, momentarily lock the rear wheels. A subsequent recall, 26V-083, also identified by GM as N252516560, covers certain trucks that may not have received the correct software calibration during the original repair.
Transmission Warnings and Valve-Body Problems: Bulletin 24-NA-188 provides diagnostic and repair information for certain transmission problems that can cause a “Service Transmission” warning, harsh shifting, a loud bang during an 8-7 downshift or other drivability concerns. These reported valve-body problems are separate from the incorrectly performed recall repairs covered by 26V-083.
Major Recalls for the Sierra 2500 HD
These recalls do not constitute every NHTSA recall that has been made to the 2500 HD. Many small, feature-specific recalls have been made for small numbers of affected trucks and are not included here. NHTSA campaign numbers are included in parentheses for reference.
Missing Owner’s Manual in Radio (26V-114 & 25V-815): Affects some 2026 models produced between August and October 2025. The vehicle radio may not have the correct owner’s manual (printed or electronic), failing Federal Motor Vehicle Safety Standards.
Roof-Rail Airbag Inflator End Caps May Detach (25V-432): The roof-rail airbag inflator end cap may detach during deployment, allowing compressed gas to escape and potentially propelling the end cap or fragments into the cabin.
Tailgate May Open Unexpectedly (24V-060 & 24V-894): Affects models 2020–2024. Water may intrude into the electronic gate-release switch, causing a short circuit and inadvertently unlatching the tailgate while parked.
Steering Gear Shaft Fracture (23V-549): The steering gear shaft may fracture, disconnecting from the steering arm and causing loss of control.
Improper Brake Control Module Installation (21V-758): Brake control module replaced during assembly may not have been bolted to spec, allowing water intrusion.
Spare Tire Mismatch (21V-578): Certain 2020-2021 trucks equipped with 17-inch accessory road tires may have an incompatible spare tire. Using the mismatched spare could interfere with ABS operation.
Incorrect Seat Belt Bolts (20V-811): Some 2020 Sierra 2500s may have the wrong seat belt fasteners installed.
Improperly Secured Seatbelt Bracket (20V-792): Certain 2020-2021 model Sierra 2500 trucks may have improperly secured seatbelt brackets on the seat frame in the front-row center seating position.
Hood Latch Striker Wires Fracture (20V-142 & 20V-324): Some hood latch striker wires may not have been heat-treated properly, leading to fractures. A follow-up recall followed for replacement hoods installed before the earlier recall.
Carpet Fires From Seatbelt Pretensioner (19V-814): Affecting some early 2020 models with carpeted flooring, some front seat belt pretensioners may vent hot gas through an opening, potentially igniting the carpet.
Sierra 2500 Technical Service Bulletins
A technical service bulletin (TSB) is service information sent to dealerships and technicians regarding proper repair procedures for specific issues. These issues are usually related to recalls, warranty claims, or common problems known to the manufacturer. The following are major TSBs relating to the Sierra 2500 HD from 2020-2026, not including those in the powertrain section above.
Tailgate Release: TSB # N232426400 / N242460160 note that the exterior touchpad switches on the tailgate can randomly open due to water intrusion, requiring a switch assembly replacement. A recall fix for recalls issued by NHTSA.
Infotainment & Audio Bugs: TSBs for the IOK radio system in emergency services vehicles. Details audio loss or malfunctioning USB receptacles. TSB PIT6247B outlines common touchscreen glitches.
No-Start or Run-On Conditions: Bulletin PIT6489 helps technicians diagnose an issue where a gas engine might continue to run even after the ignition is turned off (due to a voltage back feed in the fuel pump module).
Suspension Clunks: Bulletin #20-NA-022 offers a procedure for re-torquing the leaf spring U-bolts to eliminate a clunking noise.
Common Problems for the Sierra 2500 Heavy Duty
The following are issues commonly brought up in user/owner forums by both owners and technicians and on social media. These are issues not specifically addressed by a recall or TSB.
10-Speed Transmission Valve-Body Problems: Owners report harsh shifts, delayed engagement, getting stuck in one gear, “Service Transmission” warnings and valve-body replacements. These complaints are particularly associated with earlier Duramax-equipped trucks using the 10-speed automatic.
DEF and Emissions-System Failures: Duramax owners report failed NOx sensors, DEF quality warnings, DEF tank heater problems, exhaust-temperature sensor failures and reductant-system faults. Some faults can initiate a speed-limiting countdown until the truck is repaired.
Rear-Window and Cab Water Leaks: Water leaks have been reported around the power-sliding rear window, roof marker lights and rear cab area. The resulting water intrusion can stain the headliner and potentially affect interior electronics.
Duramax Coolant Leaks: Owners report coolant leaks involving reservoirs, hoses, fittings and other cooling-system connections. Symptoms can include visible coolant beneath the truck, a declining coolant level or a low-coolant warning.
Diesel Fuel Contamination: Water, gasoline, debris or other contamination in the Duramax fuel system can damage the high-pressure pump and injectors, potentially resulting in an extremely expensive repair.
Battery Drain and No-Start Complaints: Owners report premature dual-battery failures, unexplained battery drain, module communication errors and intermittent no-start conditions.
Fuel-System Complaints: Owners have reported hard starting, ticking, reduced power and occasional fuel-pump or injector failures. On Duramax trucks, contaminated fuel can damage multiple high-pressure fuel-system components.
How To Check For Recalls On Your GMC Truck
The easiest way to check for current recalls that may affect your 2500 HD is to visit the National Highway Traffic Safety Administration (NHTSA) Recalls page and enter your license plate or 17-digit vehicle identification number (VIN) to run a search. You can also do this at the GM Recall & Warranty Center.
