general problems of the 2021 GMC Sierra 1500 - part 1

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.

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.

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.

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 I.

Transmission valve body failure. - caused wheels to lockup momentarily and killed the engine with sudden loss of propulsion. Link to video of incident: [xxx] 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 gm TSB for the incorrect transmission fluid inside the transmission reservoir. The vehicle was not yet repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 38,875.

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 parking brake,” “check brakes,” and “check engine. ” the engine began operating abnormally. I drove directly to sewell GMC because I was concerned that the engine could fail or the vehicle could lose propulsion while in traffic. There was no crash, fire, or injury. Sewell GMC inspected the vehicle and confirmed catastrophic internal engine damage. The technician found metal debris in the engine oil and oil pan, damaged internal bearings, and camshaft/lifter damage. Sewell advised that the complete engine must be replaced. The vehicle remains at the dealership, has not yet been repaired, and the engine and failed components should be available for inspection. Before this incident, I had not experienced warning lights or symptoms indicating that an imminent catastrophic engine failure would occur. Gm and the dealership advised that my VIN is not included in the current l87 engine recall because the engine was built in 2020. However, the diagnosed bearing damage, metal contamination, and catastrophic engine failure appear similar to the engine failures addressed by that recall. I am reporting this because an unexpected internal engine failure while driving creates a serious risk of loss of propulsion and a collision.

While driving my vehicle, the engine and transmission lost power and the check engine light came on. The vehicle went into limp mode and engine propulsion was limited. Had I been traveling at a faster speed, this would have been very unsafe. After coming to a stop, placing the transmission in reverse did not move the vehicle and there was a grinding noise. I was able to savely move forward in limp mode, but the shifting was harsh. I was able to find an empty parking lot to safely park. The truck was towed to jim winter dealership in jackson mi for inspection.

When pressing on the gas, especially when moderately accelerating, the truck experiences severe shaking, which interferes with acceleration, as well as causing the truck to "jump" when the transmission gear "catches", even while driving. When the truck is at a full stop and the engine is auto off, when it restarts, it does so frequently when it reengages that it causes a physical "jump" in the vehicle, causing the driver's foot to come off the brake pedal. This has been most noticeable since my vehicle hit about 70k miles. I currently have 84k miles. I engaged the dealer and was told the transmission is out of warranty. I see that other GMC sierra models suffer similar problems and recalls have been issued to GMC that they must repair those vehicles. Despite that, my vehicle is not included in any current recall program.

While coasting down or under very light acceleration between 12-20 mph the vehicle has a shudder like driving over a highway rumble strip. While cruising on the highway at 65+ mph, the vehicle has a light shudder or vibration. Vehicle has been checked numerous times for wheel and tire inconsistencies. Brake pads and rotors have also been replaced with no change in issue. Headlights daytime running light changes color from bright white to purple during warm weather. The vehicle has been to 3 different gm dealerships and they acknowledge the issues but do not provide a resolve.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed, but the vehicle continued to move forward. There was no warning light illuminated. The vehicle was taken to the dealer and was diagnosed with transmission failure. The contact stated that the valve body and torque converter needed to be replaced. The dealer informed the contact that the transmission might need to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 65,561. The VIN was unavailable.

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 read the codes and it gave me a code p062b and I asked the dealership to look into it and they never figured out what we were not wrong. I just testing the battery. Well, then I got it back after the recall was done and new transmission valve body put in and about 30 miles down the road it started to shake violently and had a flashing engine light so I got it home called the dealership the next morning because they were closed set up another appointment got it to the dealership dealership said it had a couple misfires but since it wasn’t over 100 they weren’t concerned even though I’m pretty sure it is related to the fuel model going out because it has been cranking rapidly whenever I try to start it, but they won’t do anything to figure out what’s wrong?.

My car suffered a catastrophic engine failure, metal schards were found in the oil filter and was left out of the 2021 recall 25v274. The in service date of vehicle is March 13, 2021. The car was 83 days out of warranty when the engine failed. The truck has 47,000 miles on it. They are now trying to charge us, barter with us. They have gone from $2800 for repair, negotiated down to $100 to sign this off as a good will repair stripping us of lemon law rights and future recall remedies. Car is currently sitting at the dealership.

The 10 speed automatic transmission shakes and jumps between gears. The transmission also shakes and rumbles at cruising speeds. The diesel engine version of this truck is already recalled. My truck is a gas engine and should also be recalled. This is the same defective 10 speed transmission used in all gm vehicles and recalled in many. This vehicle needs to be recalled and fix before the wheels lock up and kill someone.

The truck randomly will not detect that it was shifted into park. Shifting between gears and back to park does not automatically fix the the issue and has taken up to 10 mins to turn the truck off. The adaptive cruise controls stopped working and can still use regular cruise control. Just not adaptive. It appears greyed out. The truck has thrown the error code: p1098, engine coolant control valve position sensor minimum stop performance. The truck would go into limp mode until the error was cleared. This error has appeared 4 times over the past five months. The most recent date of it happening was today. 06/30/2026.

Dashboard lit up with engine light and stated that there's no compulsion.

Coolant control valve has failed and caused the check engine light to occur is available for inspection. Could cause the car to overheat and cause harm to myself or others yes has been confirmed by dealer no gm has a special coverage out for the specific vehicle and model years for this vehicle, but are stating that my vehicle does not pertain to that coverage.

While driving into work, I noticed a knocking sound from the outside of the vehicle. Once parked, upon further inspection I narrowed down the area of the noise to the bottom rear of the engine/front of transmission. Fortunately, I was able to park in front of my office building and wasn’t stranded on the side of the road but under different circumstances it could've been the side of a busy highway or hours from home. I had the vehicle towed to the dealership I originally purchased from, the dealership was able to duplicate the issue with me present. Later that afternoon I was informed that the engine had failed and a replacement would be ordered. There was no prior indication of a problem or warning/cel’s. The engine failed after the dealership had completed the engine recall ( pico test and 0-40w oil change ) related to the vehicle. I am reporting this in hopes that it helps with the investigation. This has been very disappointing for me as I have supported the brand of vehicle for many years. Only to have many issues under 80,000 miles and to lose confidence in the vehicle I purchased and the company.

Power steering locked up while driving. Multiple dash lights turned on, on its own after the issue, 4wd, emergency brake, abs, and other ones im not sure what they are. Took it to the dealership for a recall and told them the issue that happened.

Power steering locked up while driving. Has been inspected and repaired by manufacturer. Recall.

With the cruise set at 55-60 mph the rpms will jump, along with a slight shudder feeling. Cruise control has turned off a few times due to this. Cruise set at 25mph and would shudder/lunge forward. Torque converter is showing it’s slipping and will need replaced. No check engine lights.

Per GMC dealership, this vehicle suffered a transmission valve body failure and they are recommending replacement of the entire transmission.

My vehicles transmission is part of a recall but my VIN is not registered for this recall repair. Please assist.

Transmission shuttering which was confirmed from from GMC dealership , but refused to do any repairs after confirmation or diagnostic and test driving. Demanded a 220$ fee be paid before releasing my vehicle back. Also gave GMC bulliten # 25-na-148 which states the same issues I'm currently having.

I have had shuddering on the highway and a few hard random diwnshifts. Last week I went to start my truck and the transmission started grinding and rattling. I was told after towing to the dealer it needed a transmission due to pump not getting enough fluid and had failed. I was told I needed to pay, even though the part causing the problem had a extended 150,000 miles and the subsequent pump failure is a result of the control valve failure.

I was driving on a highway on my way home from work. Thank god there was not a lot of traffic because my truck just shut off lost all power, then I received a message on the dash to put on neutral and restart. I tried multiple times to turn it back on. It never turned on and had to get it towed to nearest dealership. It took them a week to inform that the engine locked up even though I tried to take it for the recall they told me to wait and reschedule the appointment. Never got a new appointment until the engine failed and I got it towed to the dealership and have also not received a new kind of loaner from gm. This will be my last GMC truck I purchase.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 45 mph, the transmission inadvertently shifted from drive (d) to first gear. The check engine warning light was illuminated. The vehicle was pulled over to the side of the road and then towed to the dealer, where it was diagnosed, and it was determined that the valve body needed to be replaced. The vehicle was not repaired because parts were not available. The manufacturer was notified of the failure. The failure mileage was approximately 103,000.

I've been to the dealership a few times due to the truck jerking violently under very light acceleration when its trying to shift gears. Also there was a few times that the rear wheels have locked up while driving.

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.

The def tank in my truck is defective and its the second time in the last 14 months it has broke. The part is now back ordered and according to the dealership this is a nationwide issue regarding these specific trucks. I have contacted around 10 dealers in my area and all tell me the same thing that they have multiple trucks waiting on the same issue. I have not had my truck for over 2 months and have no idea when I will be getting it back due to dealership having no idea when the part will be released due to the back order. This seems to a huge issue with these trucks and gm is doing nothing to help resolve it. I've reached out to gm directly and get no assistance and now have made 2 payments on my truck and the dealership refuses to give me a loaner vehicle. I am looking for some help or relief on what to do to go about my issue.

On the afternoon of 01/20/26, I was merging onto the highway in my 2021 GMC Sierra 1500 when a loud bang was heard from the engine compartment at approximately 60 mph. Immediately after the ban was heard, several indicator lights on the dashboard were illuminated, including the esc, check engine light, and parking brake light. A power loss was felt when attempting to accelerate and the banging noise worsened anytime the accelerator was depressed. I was able to drive the vehicle to the nearest gm dealership that coincidentally was at the closest exit off of the highway I was traveling on. The dealership performed diagnostic and determined that the damage was caused due to the ongoing gm recall associated with safety recall n252494000. My vehicle had previously been inspected as part of the recall and was found to have passed. Vehicle had been driven approximately 4,000 miles after recall was performed.

4 months after bring my truck back to the dealership for a body valve issue on the 10 speed transmission. The truck went into limp mode while I was driving.

1-at approximately 40,000 miles, my transmission was replaced under warranty. It had been failing since approximately 2000 miles having a very hard time shifting between first and second gear. It was finally replaced at 40,000 miles. 2- at approximately 45,000 miles I took my truck into the dealership for this latest recall on the 6. 2 l failure for inspection. Vehicle is inspected and I was told I would need to have an engine replacement. I was told that there was no eta on when a replacement engine would be available and that I would be contacted when one was. Afterwards I was sent back home in the truck they just inspected for potential engine failure and said had a bad engine. As of now, I’m still waiting on a word of a new engine and my truck is still operating, but leaves me concerned that it could fail at any moment while driving it.

Driving down the road and engine shut off and would not start back. Had it towed to dealer and it needed a motor replacement. Waited over a month for the shop to finish it. New motor has 3k miles on it and is making noise, transmission is stuttering hard and the air conditioning quit working all around the same time. Had to take the truck back to the dealer after the replacement motor was installed because of a faulty “new” starter.

I believe the torque converter is failing. While driving approximately 38 mph and also 48 mph up to 51 mph the vehicle have a vibration feeling like driving on a rumble strip. If you maintain the same speed, the vibration continues if you speed up, slow down, or let off the gas it goes away. There are so many detailed explanations on forums and social media from other customers experiencing the same problem, but not seeing any recall made by GMC.