GMC Sierra 1500 loss of power problems

Filed Nov 5, 2026 · Engine, Transmission · AL

1. The engine has failed. Yes it is available upon request. 2. My safety was put at results because the vehicle loss power/pressure as I was driving. 3. Yes the problem has been confirmed by an independent service center. 4.The vehicle has been inspected by an ASE Certified Mechanic. 5. The engine light came on in the vehicle. Carshield Denied Claim, therefore I am responsible for the repairs. I spoke with GMC and it was nothing they could do and advised me to contact the federal safety agency.

Filed Nov 4, 2026 · Transmission · MS

GM has a known issue with coolant control valves that can cause vehicles to go into reduced power mode creating drive-ability and safety concerns in busy traffic situations. They have issued a TSB (N252508341) for certain VIN numbers but have ignored similar issues in other VINs.

Filed Nov 4, 2026 · Engine · WY

**Subject: Complete Engine Seizure After GM Recall Remedy – 2024 GMC Sierra Denali 1500, 6\.2L V8** I am reporting a catastrophic engine failure involving my 2024 GMC Sierra Denali 1500 equipped with the 6\.2\-liter L87 V8 engine\. At an earlier date, my vehicle underwent GM safety recall 25V274\. The dealership performed the required inspection, changed the engine oil to 0W\-40, and installed the replacement 0W\-40 oil\-fill cap\. The truck was returned to service\. On October 31, 2026, I experienced an unexpected engine shutdown while driving\. The instrument cluster displayed “Please Restart Engine\.” I subsequently brought the truck to a GMC dealership for inspection\. The dealership reported finding nothing wrong and released the vehicle back to me\. On November 3, 2026, while driving home from that inspection, I attempted to pass another vehicle\. While occupying the passing lane, my engine suddenly failed and seized without warning\. The truck lost all engine power and began coasting\. I was forced to maneuver the disabled vehicle off the roadway and into a ditch\. I contacted OnStar roadside assistance, which located my vehicle and dispatched a tow truck\. The vehicle was transported back to the dealership, where it remains\. This engine failure occurred after completion of GM’s official recall remedy and immediately following an additional dealership inspection that found no problems\. I believe this incident warrants investigation under the federal safety agency Engineering Analysis EA26005, which concerns L87 engine failures following recall repairs\. The sudden loss of propulsion during a passing maneuver created a serious collision hazard\. I request that the federal safety agency investigate this failure and evaluate the effectiveness of GM’s recall remedy\. **Vehicle:** 2024 GMC Sierra Denali 1500 **Engine:** 6\.2L L87 V8 **Mileage at failure:** 40,035 **Final failure date:** November 3 2026

Filed Nov 2, 2026 · Engine · CO

Information related to GMC 25V274 recall for 2023 GMC Sierra 1500 6.2L. Recall oil change inspection and change of oil to higher viscosity performed summer of 2025 (prior to my ownership). On May 17, 2026 the Truck lost engine power without warning and would not start again. Fortunately I was on a road and location where I could coast into a parking lot, but again the vehicle provided no advanced warning of any issue. Towed truck to dealership and determined that exact engine problem noted in recall had indeed occurred to engine. So GMC recall efforts to inspect and change oil had NO effect on the engine defect. Engine was replaced.

Filed Nov 2, 2026 · Engine · MD

Was about 1 and a half hours into my 8 hour trip home, when I started to hear a clanging sound coming from my engine after I passed a slow moving RV. The truck ran for about 20 additional minutes when it lost power and shut off. Mileage was at a little over 16,000 miles. No warning lamps, messages or other symptoms of the problem prior to the failure. I was fortunate to be pulling into a parking lot when it shut down, GMC roadside assistance had my truck towed to a GMC dealer where it was determined the engine was blown. They replaced the engine.

Filed Nov 1, 2026 · Transmission · NH

Loss of power, shuddering, hesitation upon attempt to accelerate. 8-speed automatic transmission failure, known to GMC at the time of purchase (2017). GM Service Bulletin 39370 dated April 2016.

Filed Oct 31, 2026 · Transmission · OH · fire

On XXX, my 2025 GMC Sierra 1500 AT4X AEV experienced a catastrophic failure while driving on [XXX] Oh. I had approximately 75000 miles on the vehicle when this occurred. A load explosion from underneath the vehicle and smoke, accompanied with metal thrashing noise and loss of power while in the far right hand lane of the highway. Coming to a stop, I saw fire in the grass shoulder so I inched the vehicle forward away from the fire by a couple hundred or so feet. A passing motorist called the fire department and police who extinguished the fire. I had the truck towed to Knapps Motors Chevy in [XXX]. After looking at the truck, they determined the transfer case siezed and luckily exploded the housing rather than locking up the wheels. If a motorist would have been to my right, they would have been the victim of metal shards and burning oil. This not to diminish the terrible possibility of the wheels locking while driving at 75 miles per hour. After working through GMs customer service line, they have been of no assistance whatsoever. They are pushing the repair on the extended warranty company Portfolio, who is in the process of fixing. I've been without a vehicle for more than a month, as im told the transfer case is a known issue and has an updated part number. The 2026 model year has a federal do not drive recall #26V289 due to an improperly built transfer case missing an oil pickup tube. This has been a terribly unnerving experience and feel this truck should be also involved in the recall. Please contact me at [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 30, 2026 · Engine, Steering · 34,000 miles · AK

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 45 MPH, there was an abnormal knocking sound coming from the vehicle. The vehicle started hesitating, and there was a loss of power that became worse over time. Additionally, the “Service Engine” and “Power Train” warning lights were illuminated. The messages “Loss of Steering Assist - Be Alert” and “Service Parking Brake” were displayed. The following day, the vehicle was driven in LIMP Mode to the dealer and was diagnosed with engine failure. The contact stated that there was an ongoing the federal safety agency investigation associated with the 6.2L engines. The failure mileage was approximately 34,000.

Filed Oct 29, 2026 · Fuel system · WA

On [XXX], at around [XXX] my 2023 GMC Sierra 1500 Elevation suddenly lost power while I was driving eastbound on [XXX]. The battery was still running, but the engine lost power and the accelerator did not respond and the truck would not move. I was stranded in the roadway. OnStar emailed me about a critical vehicle issue and reported DTC P129F. Because the truck was stopped in a live lane of traffic, I called 911. Responders blocked part of the road to protect me and to give the tow truck room to recover the vehicle. No one was injured, but this could easily have caused a serious collision. A few days later, I had the truck towed to Seaview GMC in Lynnwood, WA. The dealer diagnosed an internal failure of the fuel pump power control module, the K111 Fuel Pump Driver Control Module mentioned in the GM Bulletin earlier this year. This matches a known issue described in GM Service Bulletin 24-NA-139, which covers DTCs P129F and P023F and lists 2023 Sierra 1500 models. The bulletin describes symptoms including no-start and stalling. The dealership has attempted to charge me $200 for diagnosis and $261 for the fuel pump module. I had asked them if this was covered under warranty, they responded that they would check with their warranty specialist. This conversation happened at the Seaview GMC Dealer approximately 5pm on [XXX]. The informed me they would call the next day to confirm if this is covered or not covered by warranty. I am reporting this because a sudden loss of power while driving on a highway is a serious safety risk. I am concerned that other owners may experience the same failure at highway speed, and I would like the federal safety agency to review this issue. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 29, 2026 · Engine · 64,000 miles · NC

The contact owns a 2025 GMC Sierra 1500. The contact stated that while her husband was driving 10 MPH, the vehicle lost power. The driver turned off the vehicle and attempted to restart the vehicle; however, the vehicle failed to respond. No warning light was illuminated. A dealer was contacted. The vehicle was towed to the dealer where it was diagnosed and determined that the engine needed to be replaced. The engine was replaced and the vehicle was repaired. The contact stated that the engine was replaced twice. The manufacture was notified of the failure and opened a case. The approximate failure mileage was 64,000.