After 2 years of owning the vehicle, after every oil change, it would indicate low oil just before an oil change causing for us to add an additional a quart of oil to keep it running smoothly. We informed the service technician of the situation on multiple occasions and no further inspection was completed, and just an oil change was serviced. After a few months we noticed the engine was running rough and a white smoke coming out of the exhaust on acceleration then the check engine light came on. We brought the car to get tires replaced and to service the check engine light, the technician stated that the check engine light a failure in the catalytic converter. We brought the vehicle to the local GMC service center, where they indicated that the we required a replacement engine because of catastrophic engine failure. We reported that the check engine light was due to catalytic converter failure. The service technician ensured that the priority was the replacement of the full engine not indicating what was the main cause of engine failure stating that the catalytic converter could have led to the failure of the engine as well. We replaced the engine, and after 3 months of vehicle being in the shop the engine was replaced. Three days after receiving the vehicle, a check engine light came on. We did not drive the vehicle until we had to return it back to the service center. The service technician stated that it is due to a lack of communication from the engine to the ECU. The technician called the following Monday stating that the check engine light was due the catalytic converter. We told the technician that was the primary reason that the customer the vehicle in the first place. We asked if there was an alternative to replacing the catalytic converter since we already paid 12k for the engine replacement. We asked if they had taken apart the catalytic converter to confirm its not a sensor issue. They replied that the codes indicates its the whole converter.

- Parrish, FL, USA

See attached document for complaint.

- Woodhaven, MI, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving approximately 75 MPH, the rear wheels locked up. The failure had occurred on several occasions. The contact stated that several unknown warning lights were illuminated. The vehicle was towed to a dealer where it was diagnosed and determined that a software update was needed. The vehicle was repaired under an NHTSA Campaign Number: 24V797000 (Power Train); however, the failure persisted. The manufacturer was not notified of the failure. The failure mileage was approximately 35,000.

- San Antonio, TX, USA

[xxx], I purchased a 2021 GMC Sierra 1500 from faulkner Chevrolet in bethlehem, pa. I test drove the vehicle before purchase and it showed no indication of any mechanical issues that I was able to detect. I was shown by the dealership the carfax and was informed that there are currently no recalls for the vehicle. I was led to believe that the vehicle was in good condition and safe to drive and, therefore, agreed to purchase the vehicle for the aforementioned price (including tax and title fees). I purchased the vehicle with 60,077 miles on it, and after driving it normally for only 5 days (on [xxx]) it broke down and I was stranded on the highway 16 hours from home. I was able to get the vehicle towed and paid $1,200 for the starter to be replaced, which is what the mechanic suggested but this ended up being entirely unnecessary as the real issue was due to a catastrophic defect in the engine. After the starter was replaced, I was driving the vehicle only a few days later (on [xxx]) and it suffered a catastrophic engine failure while driving 70mph on the highway. I lost control of the vehicle and nearly got in a collision with another vehicle. I was able to get the vehicle to the nearest auto shop and after inspecting the vehicle they informed me that there is a serious engine issue relating to a seized bearing and the engine will need to be rebuilt entirely. At this point it had been only 12 days since the purchase and the odemeter read 61,662 (1,585 miles driven since purchase). Due to the faulty vehicle, I was forced to pay to have the vehicle shipped from the location where it broke down to the dealership where I originally bought it (around $1,200). Faulkner Chevrolet knowingly sold me an unsafe vehicle that they were well aware had a defective 6.2L V8 engine. This defect is currently under investigation by the NHTSA and faulkner Chevrolet purposefully ommitted this crucial information until after the vehicle was sold. Clearly, this is an unethical bus information redacted pursuant to the freedom of inform

- Schuylkill Haven, PA, USA

Subject: Complaint Regarding Recurring Engine Failure in 2021 GMC Sierra AT4 Dear National Highway Traffic Safety Administration, I am writing to formally express my concern regarding recurring engine failures in my 2021 GMC Sierra AT4 (6.2L engine). At 23,000 miles, the vehicle suffered a complete breakdown due to failure of cylinder #8, lifters, and push rods. General Motors covered the repairs at that time. However, at 97,000 miles, the exact same issue reoccurred, resulting in significant engine damage. The dealership diagnosed a misfire in cylinder #8, leading to the removal of the right cylinder head, where they found a bent push rod, spun lifter, damaged camshaft lobe, and lifter roller. The repair estimate totals $9,746, but GM has refused to cover the costs, despite us having an extended warranty purchased from the dealership. This recurring failure raises serious concerns about engine reliability and manufacturing defects in General Motors vehicles. I urge the NHTSA to investigate this issue, as multiple GMC and Chevrolet owners have reported similar problems with the 6.2L engine lifter and camshaft system. This is not just a costly repair but a potential safety hazard that GM has failed to properly address. Thank you for your attention to this matter. I appreciate any guidance or action the NHTSA can take to hold GM accountable and ensure consumer protection.

- Pharr (, TX, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 55 MPH, the vehicle started making a knocking sound. There were no warning lights illuminated. The contact picked up his son from school and drove the vehicle to the dealer. The contact stated that while depressing the accelerator pedal, the knocking sound became louder, and the vehicle was losing motive power. The vehicle was taken to a dealer and diagnosed with engine failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 58,522.

- Pequot Lakes, MN, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at various speeds up an incline, the vehicle was vibrating and shuddering. The failure persisted over time. There were no warning lights illuminated. The vehicle was taken to the local dealer, but the vehicle was not diagnosed or repaired. The vehicle was taken to a transmission shop, and it was determined that the transmission needed to be replaced. The manufacturer was not contacted. The approximate failure mileage was 68,000.

- West Monroe, LA, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds and depressing the accelerator pedal, the vehicle hesitated to respond and shuddered. The vehicle was taken to the dealer, where the fuel tank was cleaned, and the contact added fuel treatment to the fuel, as recommended by the dealer; however, the failure recurred. The contact stated that while driving from a complete stop, uphill, and while driving 50 MPH, the vehicle shuddered and experienced erratic transmission shifting. The check engine warning light was illuminated. The vehicle was taken to Dixie Buick GMC (14565 S Tamiami Trl, Fort Myers, FL 33912); where it was determined that the vehicle was experiencing a abnormal shudder. The dealer replaced the transmission fluid; however, the failure persisted. The contact stated that the failure had become progressively worse and mostly occurred at 1,200 RPM. The dealer was contacted, and an appointment was scheduled for diagnostic testing. The vehicle was not diagnosed or repaired. The contact related the failure to NHTSA Campaign Number: 24V797000 (Power Train); however, the VIN was not included. The manufacturer was notified of the failure. The failure mileage was approximately 8,000.

- Bean Station, TN, USA

On the morning of 1/19/25, my 2021 GMC Sierra 6.2L AT4 went into limp mode heading south on HWY 207 in Leavenworth, WA at approximately 60 m.p.h. Fortunately, I was able to avoid a rear end collision. I quickly turned the truck off in the middle of the road and restarted it with a CEL. When I returned home almost 180 miles away, my local mechanic diagnosed a code P0303 and cleared it. Since, the truck has continued to shutter at various speeds without throwing a code. It is currently at Haselwood GMC in Bremerton, WA being scanned, recorded, and findings set to GM waiting for resolve. I have notes, exact dates, times, call records, return voice mail messages, and dealership personnel spoken to, etc. The dealer-??s lead technician and I were able to replicate the shutter on a road test together on 1/27/25 at 3 p.m. after having driven just 10 miles. During my visit on the morning of 1/30/25, the lead technician stated he has since been able to replicate the shutter seemingly getting worse. I was strongly encouraged by the service manager, service writer, and lead technician their collective -??personal recommendation-?? was to not take the truck back. Haselwood has had the truck since 1/27/25. Still awaiting a response and resolution.

- Seabeck, WA, USA

The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 24V797000 (Power Train); however, the contact believed that the remedy offered would cripple the vehicle and interfere with his work. The contact works in Alaska and the remedy involved the transmission being limited to fifth gear, preventing the possibility of a wheel lock up condition, which could occur while downshifting from eighth gear. The manufacturer was made aware of the issue and advised the contact to find a dealer that could repair the transmission. The contact had not experienced a failure. Parts distribution disconnect.

- Palmer, AK, USA

The engine locked up with no warning I called the dealership and they said it was out of warranty as it has 77000 miles. upon further investigation I found that the front main bearing on the engine had gone bad and caused the engine to lock up. GMC refused to accept any responsibility for the failure.

- Ravendale , CA, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at approximately 20 MPH, the vehicle lost motive power. The contact stated that the accelerator pedal was depressed; however, the vehicle failed to respond as needed. The contact moved the transmission lever from drive(D) to neutral(N) to reverse(R) several times and was able to drive back to the residence. The contact stated that the check engine warning light was illuminated. The contact had the vehicle towed to a local dealer. The dealer diagnosed the failure and determined that the transmission control valve had failed and needed to be replaced. The vehicle was repaired; however, the contact stated that the failure had reoccurred. The vehicle was taken back to the same dealer who advised that the transmission control valve had failed, but the parts needed to complete the repair were on back-order. The vehicle was not repaired. The contact had asked the dealer what the possibility of the same failure reoccurring after the second replacement of the control valve and the dealer advised that the valve would fail again. The vehicle was awaiting repair. The manufacturer was informed of the failure. The failure mileage was 27,676.

- Knoxville, TN, USA

The control valve system on my 2021 gmc has malfunctioned and this is the second time, currently sitting at Nelson GM Dealer in Fergus Falls MN. I have to drive back to TN as thats where I live and the mechanic said this issue will happen again. This vehicle hasn't had recalls but I believe it was missed since this is the second time with this same issue. This is a GM wide issue as I have researched.

- Knoxville, TN, USA

We had to replace the transmission at 70,000 miles even though problems were reported to the dealer at 53,340. This repair costed $2300 on a 1 year old truck. Then we needed to replace a solenoid circuit which was not covered under warranty. We repaired this 2x (the second time covered). Then at 147,000 miles 9/24, there was a cylinder misfire which bent the push rod and collapsed lifter. This engine repair cost $8300 dollars. Who has to replace an engine on a truck that's 3 years old. This is a defect. Please help us. We have spent over $10,000 on repairs. We faithfully do our changes and service.

- Sanbornton, NH, USA

L87 engine problems. I have had failed lifters, on top of transmission issues and a current oil consumption issue where I have to add two quarts of oil (sometimes more) without any indication of low oil. I took my vehicle into the local dealership and the technician asked if I had gotten any low oil indicator and I stated no. He proceeded to tell me it had little to no oil in it. Imagine this at highway speeds and sudden engine seizure.

- Spruce Pine, NC, USA

Transmission has a hard shift when coming out of each gear. 2nd to 1st shifts hard and jolts entire vehicle a head. Feels like a slip or difficulty in shift.

- Navajo, NM, USA

I received a notice of a recall for a known problem with GMC transmissions. it is very well known that these transmissions lock up and cause problems with braking and can cause the vehicle to slide off the road when the tires lock up. it also causes hard shifting, which I have experienced. GMC said they will not fix the transmission, they instead will add a device to monitor the transmission, so when the transmission locks up and causes an accident, it will let me know that it was the transmissions fault!!! How is this legal" they will let me know that their transmission caused the accident after the fact? why not fix it" typical of government to do nothing about safety... and instead make laws that allow big corporations and government to make money off of peoples deaths!

- Milton, FL, USA

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at various speeds and downshifting, the rear wheels locked up with the parking brake warning light flashed on the instrument panel. The vehicle would resume normal operation soon after the failure. The vehicle was taken to a dealer where the contact was informed that there was a pending NHTSA Campaign Number: 24V797000 (Power Train) on the vehicle for the failure. The contact was informed that there was a temporary fix on the vehicle to repair the defect. After the temporary fix was performed, the contact experienced the failure twice within a week. The contact received a call that the permanent fix was available; however, soon after the repair was performed, the failure immediately occurred upon leaving the dealer. The manufacturer was notified of the failure, and the contact was informed that he would receive a callback. The vehicle was not repaired. The failure mileage was approximately 75,000.

- Goshen, OH, USA

The contact owns a 2021 GMC Sierra 1500. The contact received notification of NHTSA Campaign Number: 24V797000 (POWER TRAIN); however, the part to do the recall repair was unavailable. The local dealer was contacted, and it was confirmed that the part was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact stated that the transmission was shifting hard while driving. The local dealer was notified of the failure. The cause of the failure was not yet determined. The manufacturer was not made aware of the issue. The failure mileage was 120,000. VIN tool confirms parts not available.

- Coeburn, VA, USA

transmission has a shudder when accelerating and after shifting through all gears (8speed) during cruise mode when going on an incline as in overpass it starts to shudder and seems like it is trying to find the right gear to go into.

- Grubbs, AR, USA