2021 GMC SIERRA 1500 Safety Overview

Component: ENGINE

"The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving and towing a 5,000-pound load, the vehicle made an abnormally loud sputtering sound at 3,000 RPM. The contact stated that the failure was more noticeable while towing a load. The vehicle was taken to an independent mechanic, where an audible diagnostic test was performed and the contact was informed that the sound was related to the engine bearings. The vehicle was then taken to the dealer, where it was diagnosed with fifty-two engine misfires. The contact was informed that the misfires should have caused the check engine warning light to illuminate; however, the light was not illuminated. The dealer replaced the ignition coils and spark plugs; however, the failure recurred while driving. The manufacturer was notified of the failure. The failure mileage was approximately 110,000."

Component: ENGINE

"Truck was in motion and the engine light started blinking then stopped. A couple miles down the road the truck jilted and the engine light came on again. The Service ESC and emergency parking brake light came on. The truck started shaking. We pulled over and parked. Turn off the truck and when we turned it back on it started shaking. When we drove we started hearing popping, knocking, loss in power of the vehicle. This could’ve caused serious damage to ourselves or other drivers if we could’ve have stopped. Vehicle is being inspected. Multiple same vehicles have had the same issues in my town. At least 5 that we know of. At one point all of the lights came on and now there is just a few lights. More than what I listed earlier."

Component: POWER TRAIN

"The transmission overheats on this vehicle shutting the vehicle into “limp mode” this is extremely dangerous when at interstate/highway speeds and the vehicle slows it self down to a dangerously low speed and all other vehicles around are traveling at a high rate of speed, this has happened twice, it has also happened while in back roads and tractor trailers have had to swerve to avoid a collision."

Component: ELECTRICAL SYSTEM,ENGINE

"The contact owns a 2021 GMC Sierra 1500. The contact stated that while the vehicle was parked, the battery charge indicator to zero. The vehicle lost motive power, and the vehicle was unable to exceed 30 MPH while driving. The vehicle was driven in LIMP Mode. The battery saver mode message was displayed before and during the failure. The vehicle then failed to restart. The vehicle had been repaired a year prior to the failure. The contact's blood pressure became elevated due to the issue. The failure mileage was approximately 98,000."

Component: ENGINE

"Excessive oil consumption. I am fearful that my vehicle engine will lock up."

Component: ENGINE,FUEL/PROPULSION SYSTEM

"On [XXX], my vehicle suffered a complete loss of propulsion on the highway, displaying fault codes P0324 and P0016. The vehicle was taken to Boyd's Tar Heel Chevrolet in Roxboro, NC, where the engine block was replaced under the official GM 6.2L engine safety recall.The truck was delivered back to me, and on the very first day I drove it—only 28 miles from my house—it suffered a secondary catastrophic loss of propulsion on the highway on [XXX]. The check engine light began flashing violently, indicating an immediate catalyst-damaging safety hazard, and the vehicle displayed fault code P0307 (Cylinder 7 Misfire).The dealership explicitly instructed me to stop driving the vehicle immediately, authorized the recovery, and told me to bill the tow directly to them. After towing the vehicle back to their facility, Boyd's Tar Heel Chevrolet reversed their position. They are now attempting to hold me financially responsible for the towing fees, along with spark plugs, wiring, and fuel injector services, claiming the failure is due to routine maintenance.This represents a severe highway safety hazard, a direct failure of the manufacturer's official recall remedy, and potential dealer misconduct to avoid liability under the active NHTSA Engineering Analysis EA26005 for post-recall 6.2L engine failures. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: ENGINE

"There is an known issue with the coolant control valve that causes the truck to enter "limp mode" that dangerously reduces the engine power. The part is not recalled but there is a special extended warranty, N252508341, up to 15yrs or 150,000 miles for 2021-2022 GMC 1500 trucks but my VIN is excluded from this for some reason. I would like this investigated."

Component: ENGINE

"While driving 40 MPH my entire dash lite up with every known light and the vehicle lost all power. The dealer stated I need an entire engine replacement, as with Many 6.2. My vehicle is 1 months out side of the recall, it has the exact symptoms and the exact damage as the recall."

Component: LATCHES/LOCKS/LINKAGES

"The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at various speeds, the tailgate opened independently. The failure occurred several times and became more persistent recently. The contact stated that while the vehicle was parked in the driveway, the side marker lights started flashing, and the tailgate opened. Additionally, upon exiting a store, the contact discovered that the tailgate had opened while the vehicle was parked. The dealer and the manufacturer were notified of the failure and confirmed that the VIN was not included in a recall. The failure mileage was approximately 66,000."

Component: POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM

"1. I am being told that the high-pressure fuel pump (HPFP) catastrophically seized and locked up internally while driving. Because the HPFP on the 3.0L Duramax (LM2) engine is directly driven by the engine's timing system, this sudden mechanical seizure instantly destroyed the engine timing gears and snapped/skipped the timing chain. The failed components are currently intact inside the vehicle and are fully available for inspection upon request at Ron's Smith GMC in Merced, CA. 2. The failure occurred on busy Labor Day (XXX) while our family of [XXX] was traveling back home at 70 mph on a major highway. The truck violently shook, instantly lost all engine power, and forced the vehicle into a dangerous limp-mode state before completely stalling in live highway traffic at night around 10:45 pm. This sudden loss of propulsion at high speed severely compromised our ability to safely navigate out of the way of fast-moving highway traffic, creating an immediate & extreme risk of a high-speed rear-end collision. At times hazard lights didn't work causing family panic & screaming as truck shook with passing traffic. 3. The problem has been officially confirmed by Ron Smith GMC in Merced, CA. Their service department diagnosed the issue, confirming that the high-pressure fuel pump had locked up and subsequently destroyed the timing belt/chain & engine gears. 4. The vehicle and its failed components have only been inspected by technicians at the Ron Smith GMC dealership service department. No police, insurance representatives, or outside third parties have inspected the vehicle yet. 5. I had been extremely happy with my truck and there were absolutely no warning lamps, dashboard messages, or driving symptoms prior to the failure. The truck was operating perfectly normally under cruise until the exact moment of the failure, at which point a "Reduced Engine Power" warning flashed on the dashboard simultaneously with the mechanical lock-up, shaking, and immediate stall. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: POWER TRAIN,ENGINE,FUEL/PROPULSION SYSTEM

"1. I am being told that the high-pressure fuel pump (HPFP) catastrophically seized and locked up internally while driving. Because the HPFP on the 3.0L Duramax (LM2) engine is directly driven by the engine's timing system, this sudden mechanical seizure instantly destroyed the engine timing gears and snapped/skipped the timing chain. The failed components are currently intact inside the vehicle and are fully available for inspection upon request at Ron’s Smith GMC in Merced, CA. 2. The failure occurred on busy Labor Day (XXX) while our family of [XXX] was traveling back home at 70 mph on a major highway. The truck violently shook, instantly lost all engine power, and forced the vehicle into a dangerous limp-mode state before completely stalling in live highway traffic at night around 10:45 pm. This sudden loss of propulsion at high speed severely compromised our ability to safely navigate out of the way of fast-moving highway traffic, creating an immediate & extreme risk of a high-speed rear-end collision. At times hazard lights didn’t work causing family panic & screaming as truck shook with passing traffic. 3. The problem has been officially confirmed by Ron Smith GMC in Merced, CA. Their service department diagnosed the issue, confirming that the high-pressure fuel pump had locked up and subsequently destroyed the timing belt/chain and engine gears. 4. The vehicle and its failed components have only been inspected by technicians at the Ron Smith GMC dealership service department. No police, insurance representatives, or outside third parties have inspected the vehicle yet. 5. I had been extremely happy with my truck and there were absolutely no warning lamps, dashboard messages, or driving symptoms prior to the failure. The truck was operating perfectly normally under cruise until the exact moment of the failure, at which point a "Reduced Engine Power" warning flashed on the dashboard simultaneously with the mechanical lock-up, shaking, and immediate stall. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: ENGINE

"Lifter collapsed at 31970 miles. It was fixed at GMC dealership. It just happened out of no where. No warning signs."

Component: ELECTRICAL SYSTEM,VEHICLE SPEED CONTROL

"Dashboard keeps returning to aljarir type writing. We bought it with American English but won't stay in English. Monday will be 30 day and I believe the dealer is ghosting me. Y'all have any ideas how to reset the dashboard without replacing the radio??? Closest answer I was given."

Component: POWER TRAIN

"I own a 2021 GMC Sierra 1500 AT4 with the 3.0L Duramax diesel. The vehicle developed severe transmission problems, including harsh/jerky shifting and a hard clunk when shifting into reverse. The vehicle was subsequently diagnosed with an internal transmission failure. The repair facility informed me that the transmission gears had failed and caused damage to the transmission and stated that the failure appeared to be related to a manufacturing issue. The repair facility also advised me to watch for a future recall because they believed this could be a widespread issue occurring in other vehicles. I am submitting this complaint so the failure can be documented and considered along with other reports of transmission failures involving this vehicle.NOTE FROM AUTOSHOP:TRANSMISSION FAILURE WAS DUE TO A MANUFACTURE DESIGN FLAW, NOT DUE TO THE CUSTOMER'S DRIVING HABITS. THE PUMP ORIGINAL DESIGN IS WITH SLANTED GEARS AND THE GEARS ARE FORCED AWAY FROM EACH OTHER AND PLACING TOO MUCH STRAIN THE BEARINGS ANI THE BEARING FAIL. AN UPDATE PERFORMED TO HAVE STRAIGHT CUT PUMP GEARS TO AVOID BEARING DAMAGE. CDF DRUM AND CENTER SUPPORT CHANGED TO UPDATED PARTS THAT ARE HEATED TREATED TO AVOID DAMAGE"

Component: POWER TRAIN

"Purchased a used 2021GMC SIERRA in Mar. 2025 from W&K GMC Sedalia Mo. Two mths ago ([XXX]) noticed an occasional slipping in transmission, wheels lock up. The truck would slip, lock for 1-4 seconds and then return back to normal driving. Has done this while accelorating and while driving down the highway. I took truck to my local repair garage who indicated it was most likely the torque converter and it would need to be taken to the dealership for repair. After mechanic commenting that he had seen several GMCs with the same problem, I looked up GMC recall and found that this issue did have a recall on 2020 - 2022 GMC SIERRA TRUCKS ( ours is a 2021)! When my VIN did NOT show any recalls, I called W& K GMC in Sedalia on 9-23-26 and spoke with the shop who told me MY truck did not have the recall notice and it would cost me $160 out of pocket for a diagnostics and $600 -$800 for a converter to even be flushed to see if problem resolved PRIOR to any part replacement. They would have to charge me full price for this repair since MY VIN DID NOT HAVE A RECALL, BUT THE SAME TRUCK MODEL, YEAR, AND ENGINE HAS OTHER RECALLS? I called GMC customer service line on 9-23-26, spoke with customer service agent Tanika, she documented the same info. and could not explain why a 2021 Sierra with the same problem as a 2020-2022 Sierra was not included in this recall that it must have been manufactured in a different facility? The fact that my local garage mechanic in a very small town, has already seen SEVERAL GMC trucks with the SAME PROBLEM, leads me to believe this is a WIDE SPREAD PROBLEM, that GMC is choosing to ignore due to the cost of repairs involved. I am requesting an investigation into HOW MANY RECALLS HAS GMC SENT OUT AND REPAIRED? AND SPECIFICALLY WHY AFTER 3 YRS OF PRODUCTION BY GMC DO THEY BELIEVE A TRANSMISSION PROBLEM WAS ONLY CERTAIN VEHICLES AND NOT ALL THE VEHICLES? This is a huge safety concern if wheels lock up on hwy at 70mph due to malfunctioning TC INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: UNKNOWN OR OTHER

"NUMERO DE VIN FALTANTE"

Component: SUSPENSION,ENGINE

"Both of my upper ball joints wore out and one broke as I was driving down the road at 65 miles an hour pulling me into the on coming lane of traffic, there was no warning of this. I had both upper and lower ball joint replace. If there had been another vehicle coming in the on coming lane we would have had a head on collision. At an earlier date the motor in this same truck had a fallen lifter which cause my motor to loss power, I was able to take it to the local GM dealer and they fixed it, there was no warning this was happening either. I am worried I will have a catastrophic engine failure and GM will not cover this. I have looked up my"

Component: STEERING,SUSPENSION,STRUCTURE

"Vehicle Safety Hazard Summary: This complaint concerns an incomplete, non-compliant post-collision structural repair on a 2021 GMC Sierra 1500 (VIN: [XXX]). It has resulted in immediate vehicle tracking failure, dangerous steering drift, and a compromised cabin safety cage following a passenger-side side-impact collision. 1. Severe Suspension and Tracking Misalignment • Electronic Alignment Failure: The post-repair electronic wheel alignment documents a Rear Thrust Angle of 0.17°. General Motors OEM specifications require a maximum allowable thrust angle of 0.10° or less for this 4WD Crew Cab chassis. The system printed a critical warning: "One or more values are not within specification. Tire wear, handling and safety problems may result." • Physical Wheelbase Displacement: Physical cross-measurements confirm a 1.25-inch tracking variance between the rear wheel wells. This proves the solid rear axle has shifted along the leaf springs due to a sheared centering pin or a bent axle/spindle assembly. • Road Hazard Handling: The truck exhibits a severe right-hand steering drift. The driver must hold the steering wheel significantly off-center to prevent the vehicle from pulling off the road. This creates an immediate risk of control loss during highway driving, sudden avoidance maneuvers, or wet weather. 2. Compromised Cabin Structure and Latch Failure • Structural Binding: The facility performed an outer B-pillar sectioning repair. Upon delivery, the B-pillar door check bracket was left un-torqued. When this structural hardware is torqued to factory specifications, the passenger door binds severely against the cab shell and will not latch or close without being violently slammed. This mechanical binding confirms the underlying inner high-strength steel pillars remain deformed, compromising side-impact and rollover crashworthiness. The vehicle is mechanically out of safe operating specifications, and the repair facility refuses to perform further corrections INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: POWER TRAIN,ELECTRICAL SYSTEM,ENGINE

"Received Re-Call for Engine Failure! Dealer replaced Engine Oil and Oil Cap @ 85,544 Miles. I read of the Re-call prior to the notice and I waited for it to come. After I received it and the Dealer made the changes, it made me afraid to leave town using my truck for fear of a breakdown on the Freeway. I use a Walker, so if I broke down and I was in the left lane and lost all power it would be very dangerous for me to get to the right side of the road! The truck started using excessive Oil after they changed the oil. I replaced four (4) quarts of oil @ 2526 miles! Speedometer reading 88070 miles."

Component: POWER TRAIN

"The contact owns a 2021 GMC Sierra 1500. The contact stated that the transmission was previously replaced. The contact stated that 20,000 miles later, the vehicle started to experience erratic hard shifting while driving at various speeds, and the vehicle failed to respond upon shifting into reverse(R). The vehicle was towed to the dealer, where the battery was replaced; however, the failure recurred. The contact received notification of NHTSA Campaign Number: 24V797000 (Power Train). The vehicle was towed back to the dealer, where it was determined that the transmission needed to be replaced. The contact was advised that the repair was not covered under the extended warranty coverage associated with the recall because the required DTC was not retrieved. The contact advised the dealer to complete the TCM software update under the recall, which would enable the generation of warning lights and DTC. After several attempts, the dealer informed the contact that the TCM software update was unsuccessful. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was notified of the failure by phone and email, a case was filed, and documents were sent to the manufacturer. The failure mileage was approximately 38,000."