2021 GMC Sierra 1500 Common Problems & Defect Telemetry
Authoritative defect intelligence synthesized from 534 verified NHTSA owner complaints, 7 federal safety recalls, and interquartile failure mileage telemetry.
The 2021 GMC Sierra 1500 receives a 5.2/10 MazicBay Reliability Index based on 534 verified NHTSA federal complaints and 7 safety recalls. The primary reported failure mode is Engine Stalling, Oil Consumption & Cooling Defect Reports with a median failure point at 24,000 miles (IQR: 8,116 – 63,500 mi). Out-of-warranty repairs benchmark at $950 – $3,200 .
20.5 complaints / 10k sold
Verified US federal records
Crash, fire & stall audit
7 Active / Free Remedies
Top Reported Problem Clusters (7)
Engine Stalling, Oil Consumption & Cooling Defect Reports
- Engine sudden stall / hesitation while driving
- Abnormal oil burning / consumption
- Check Engine Light (MIL) flashing
- Engine overheating / coolant loss
“2021 6.2L GMC Sierra Denali. Has the L87 engine that is recalled but yet my truck doesn’t fall under the recall although the recall is for 2021-2024 engines. Everything that the engine recall states is the issue with my truck, I have service report from dealership stating that...”
“Push on accelerator truck barely would go, shifted hard, codes check engine lights flashing, engine sounded bad”
“Transmission Valve Body failure. - Caused wheels to lockup momentarily and killed the engine with sudden loss of propulsion. Link to video of incident: ... INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)”
Transmission Hesitation, Hard Shifting & Slipping Reports
- Hard gear shifts / delayed engagement into Drive/Reverse
- Transmission shudder / jerking under acceleration
- Transmission slipping between gears
“Push on accelerator truck barely would go, shifted hard, codes check engine lights flashing, engine sounded bad”
“Transmission Valve Body failure. - Caused wheels to lockup momentarily and killed the engine with sudden loss of propulsion. Link to video of incident: ... INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)”
“The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission was shuddering, especially while driving uphill. The dealer was contacted, and the vehicle was diagnosed and determined to have a failure associated with a ...”
Electrical Parasitic Drain, Infotainment & Harness Reports
- Unexplained battery drain after sitting overnight
- Infotainment display / instrument cluster blackouts
- Accessory malfunction / alternator fault warnings
“I am submitting supplemental evidence regarding my 2021 GMC Sierra (VIN ...) for Recall Query RQ26001, Campaign 25V-274. Despite multiple repair attempts, my vehicle remains unsafe and non-compliant with GM Service Bulletin N252494002. The recall remedy was performed deficient...”
“I own a 2021 GMC Sierra AT4 3.0L Duramax (VIN ...). The vehicle has codes P1098 (Coolant Control Valve Performance) and P129F which coincides with the first code. My dealer believes this is consistent with an Engine Coolant Control Valve failure. I understand Special Coverage ...”
“When I put the vehicle in park, the dash warning says it is not in park or shift to park. The components continue to work. I have taken it to the dealership and according to the service manger, this is a very common occurrence in these trucks. This seems to me that it would be...”
Service Brakes, ABS Actuator & Master Cylinder Reports
- Spongy or hard brake pedal travel
- ABS / Brake warning light illuminated
- Extended stopping distance / pedal vibration
“Vehicle: 2021 GMC Sierra SLT | VIN: ... Dealership: Carl Black GMC Roswell, GA (11225 Alpharetta Hwy, 30076) | Invoice #... | Service Date: ... Paragraph 1 – Suspension Hazard: Dealership diagnosed a worn left upper ball joint (popping sound on left turns) and installed Rough ...”
“On June 25, 2026, at approximately 84,000 miles, while traveling approximately 60-65 mph on Highway 121 in a posted 65 mph zone, driving my 2021 GMC Sierra 1500 AT4 equipped with the 6.2L L87 engine, multiple warning messages suddenly appeared, including “Check ESC,” “Check Pa...”
“I am submitting supplemental evidence regarding my 2021 GMC Sierra (VIN ...) for Recall Query RQ26001, Campaign 25V-274. Despite multiple repair attempts, my vehicle remains unsafe and non-compliant with GM Service Bulletin N252494002. The recall remedy was performed deficient...”
Electric Power Steering Assist & Suspension Noise Reports
- Sudden loss of electric power steering assist
- Steering wheel pull or highway wander
- Clunking / knocking noise over bumps
“A small drip started approximately 18 months ago from top middle of left side window in rear slider. It was first mistaken as blow by from car wash. Leaking slowly progressed to dripping down middle of both side windows in rear sliders. Leaking progressed to drops coming from ...”
“CORRODED GROUNDING STRAP FAILED CYLINDER 5 GLOW PLUG CIRCUIT CRACKED AND SEPARATED EXHAUST BACKPRESSURE VALVE”
“Vehicle: 2021 GMC Sierra SLT | VIN: ... Dealership: Carl Black GMC Roswell, GA (11225 Alpharetta Hwy, 30076) | Invoice #... | Service Date: ... Paragraph 1 – Suspension Hazard: Dealership diagnosed a worn left upper ball joint (popping sound on left turns) and installed Rough ...”
Fuel Pump Pressure Loss & Fuel Delivery Defect Reports
- Sudden loss of propulsion power at highway speeds
- Extended engine cranking / failure to restart
- Fuel odor near fuel tank / engine bay
“So I made an appointment to have my truck recalled and the Wednesday before I took it, and it cranked no start and I called the dealership. Ask if they had any other those like this and they said that it could be the fuel injector module and so I got it to a mechanic shop to r...”
“Began with a misfire on cylinder 5 code P0305. Replaced spark plugs, wires, and coil pack. Misfire still existed. Fuel injector on cylinder 5 was stuck open and had to be replaced. Misfire still existed. No spark from new coil pack on cylinder 5, replaced coil pack connector. ...”
“The contact owns a 2021 GMC Sierra 1500. The contact stated that after driving on a trip, the contact noticed that the vehicle had lost 10 MPG after a software update was performed. The check engine warning light was illuminated. The vehicle was taken to Richardson Chevrolet (...”
Airbag Occupant Detection & Inflator Defect Reports
- SRS Airbag warning lamp illuminated
- Passenger occupant classification sensor failure
- Seat belt retractor lockup
“The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 5 MPH, the vehicle lost proper steering ability, and the steering wheel became loose and spun around in a circle. The air bag message was later displayed on the instrument panel. Upon inspecting the...”
“2021 GMC Sierra 1500 ... miles 36,500. My childs seatbelt does not work and the lane keep assist does not work INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)”
“• The airbag system failed to deploy during a collision that resulted in the total loss of the vehicle. Additionally, the vehicle was operating with a 17” spare tire (undersized compared to the standard 20” wheels), which may have contributed to the accident. The vehicle has b...”
Official NHTSA Safety Recalls (7)
SEAT BELTS
Summary: General Motors, LLC (GM) is recalling certain 2019-2021 Chevrolet Silverado 1500 and GMC Sierra 1500, 2021 Chevrolet Suburban and Tahoe and GMC Yukon XL and 2020-2021 Chevrolet Silverado 2500 and 3500 and GMC Sierra 2500 and 3500 vehicles. The seat belt brackets may not be secured to the seat frame in the front-row center seating position.
SEAT BELTS
Summary: General Motors, LLC (GM) is recalling certain 2020 Chevrolet Bolt EV and 2021 GMC Canyon and Sierra 1500, 2500 and 3500, Yukon, Yukon XL, Cadillac Escalade and Escalade ESV and Chevrolet Blazer, Camaro, Colorado, Equinox, Silverado 1500, 2500 and 3500, Suburban and Tahoe vehicles. Incorrect bolts may have been used at one or more fastening locations to secure the seat belts to the vehicle. If an incorrect bolt was used, the seat belt may not be properly attached to the vehicle.
TIRES
Summary: General Motors LLC (GM) is recalling certain 2020 Buick Enclave, Cadillac XT5, GMC Acadia and Chevrolet Traverse vehicles and 2020-2021 Chevrolet Silverado 1500, GMC Sierra 1500 vehicles. The vehicles may have been manufactured with Continental tires that were overcured.
TIRES:TEMPORARY/EMERGENCY SPARE TIRE
Summary: General Motors (GM) is recalling certain 2019-2021 GMC Sierra 1500 and Silverado 1500 vehicles equipped with certain accessory road tires and a 17" spare tire. The 17" spare tire provided with the vehicle is not compatible for use with the accessory wheels, which can cause the anti-lock brake system (ABS) to not function properly under certain conditions.
POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE
Summary: General Motors, LLC (GM) is recalling certain 2020-2022 Chevrolet Silverado 1500, 2500, 3500, GMC Sierra 1500, 2500, 3500, 2021 Cadillac Escalade, Escalade ESV, Chevrolet Tahoe, Suburban, GMC Yukon, and Yukon XL vehicles equipped with diesel engines. The transmission control valve may fail and cause the rear wheels to lock-up.
ENGINE AND ENGINE COOLING:ENGINE:HARD PARTS INTERNAL/MECHANICAL
Summary: General Motors LLC (GM) is recalling certain 2021-2024 Cadillac Escalade and Escalade ESV, Chevrolet Silverado 1500, Suburban, and Tahoe, GMC Sierra 1500, Yukon, and Yukon XL vehicles equipped with a 6.2L V8 gas engine. The connecting rod and/or crankshaft engine components may have manufacturing defects that can lead to engine damage and engine failure.
POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE
Summary: General Motors, LLC is recalling certain 2020 Chevrolet Silverado 2500, 3500, GMC Sierra 2500, 3500, and 2020-2022 Chevrolet Silverado 1500 and GMC Sierra 1500 vehicles that may have been repaired incorrectly under recall 24V797. The transmission control valve may fail and cause the rear wheels to lock up.
Pre-Purchase Inspection Checklist for 2021 GMC Sierra 1500
Before purchasing a used 2021 GMC Sierra 1500, perform the following targeted inspections based on reported federal defect patterns:
Scan the OBD-II port under the dash for pending freeze-frame codes (e.g. P0300 misfires, P0087 fuel rail pressure, P0420 catalytic efficiency).
Test vehicle at low-speed stop-and-go and highway merges. Check for delayed reverse engagement or gear shift shudder between 2nd and 3rd gears.
Verify that all 7 NHTSA safety recall campaigns have been performed by an authorized dealership using the VIN.
Ensure the instrument cluster, center screen, and auxiliary charging ports operate with stable 12.0V–14.4V alternator voltage.
Defect & Reliability Q&A: 2021 GMC Sierra 1500
Is the 2021 GMC Sierra 1500 a reliable used car?
The 2021 GMC Sierra 1500 earns a 5.2/10 MazicBay Reliability Index based on 534 federal owner reports. Vehicles maintained under factory service schedules exhibit strong longevity past 150,000 miles.
What is the most frequent defect reported on the 2021 GMC Sierra 1500?
The leading complaint category is Engine Stalling, Oil Consumption & Cooling Defect Reports, with a median failure point around 24,000 miles (IQR: 8,116 – 63,500 mi).
Are there free recall repairs available for the 2021 GMC Sierra 1500?
Yes, the NHTSA records 7 safety recall campaign(s) for this model year. All safety recalls are performed 100% free of charge by authorized franchise dealerships regardless of vehicle warranty status.