2021 GMC Sierra 1500: engine stalls while driving

Filed Oct 18, 2026 · Brakes, Engine · LA

Service light came on because the brake petal would push back when I tried to start it. At times, I had to push down all the way almost to the floor and then it would start. If I eased up slightly or did not push all the way, the truck would hesitate to start. I brought it in to Courtesy GMC of [XXX]. They found metal debris in oil. The car warranty did not want to replace the entire engine as General Motors' bulletin had stated as a corrective solution. They only wanted to replace the camshaft and rocker arms because [XXX] did not tear down the engine to the point of failure. [XXX] stated that they did. After going back and forth with EasyCare (myself and [XXX]) I authorized the repairs EasyCare suggested. XXX, a Service Brake Assist message came on. I brought it to [XXX]. They rectified the issue. XXX,Truck stalled getting off XXX at light. Truck kept turning on and off. I put it in park and was able to turn in on. As I was driving the truck was rocking back and forth as I pressed the gas pedal. I was able to pull into the Super1 Foods parking lot. Trucked stalled halfway into parking lot. After two attempts to turn off and start truck I was able to pull it up all the way to ensure safety. Texted [XXX] at Courtesy. I called the number he sent and a tow truck from Cliff’s Towing and Recovery, LLC retrieved my truck and brought it to Courtesy GMC in [XXX] where it is currently residing. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Oct 18, 2026 · Fuel system · FL

The vehicle failed to start. It started after 30 minutes and I was able to drive it home. Then it starts and stalls after multiple attempts. Receiving codes P1177 and UI8A2. Was told that a bulletin exists for this issue on GM vehicles, GM Bulletin 24-NA-139, but I found out that it don't cover my VIN number. This can cause the vehicle to stall or shut off while driving. GM should make this bulletin for all vehicles of certain years who carry this modules.

Filed Oct 1, 2026 · Engine, Fuel system · CA

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

Filed Sep 30, 2026 · Engine, Fuel system · CA

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

Filed Sep 10, 2026 · TX

The engine coolant control valve on my 2021 GMC Sierra 3.0L Duramax diesel failed. This specific component failure triggers an active vehicle 'No-Restart' safety event during automatic engine stop/start operations (per GM Service Bulletin #24-NA-070). This condition can suddenly prevent the vehicle from restarting when stopped at intersections or in active traffic, creating an immediate highway safety hazard and leaving the vehicle stranded. Additionally, the vehicle's radiator cooling fans run continuously at 100% maximum capacity as a system fail-safe, creating severe electrical drain. General Motors has issued a Special Coverage Adjustment (#N252508341) acknowledging the high failure rate of this part, but it is capped at 150,000 miles. Because this defect causes unexpected stalling/no-start safety risks in live traffic past this arbitrary mileage limit, a formal safety recall is required.

Filed Aug 25, 2026 · Engine, Transmission · MO

For close to one year, there feels like a catch, grind, stall, or slight shake, mostly while the vehicle is shifting gears, made worse or noticed more by higher speeds like driving on the highway vs. slow city streets. It's difficult to explain or assess so not sure if it is the engine or transmission. With the open recall from GMC on some vehicles with the same engine as mine it is concerning that maybe it should have been included.

Filed Jul 29, 2026 · Engine · 149,000 miles · OK

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving approximately 70 MPH, the vehicle suddenly lost motive power, decelerated, and failed to properly accelerate while depressing the accelerator pedal. The check engine warning light was illuminated. After exiting the freeway, the vehicle stalled. The vehicle was towed to the residence and then later towed to the dealer for assistance. The contact was informed that there were metal shavings inside the engine oil. The contact was informed that the engine needed to be replaced. The vehicle was not yet repaired. The contact was informed that the VIN was not included in the federal safety agency Campaign Number: 25V274000 (ENGINE AND ENGINE COOLING). The contact stated that the vehicle had experienced the failure listed in the recall. The manufacturer was not yet contacted. The failure mileage was 149,000.

Filed Jul 14, 2026 · Engine · MI

I was driving and my check engine light came on a mile from my house. I drove home and the next morning, I started my truck. It was loud and pulsating like it wanted to stall out. I had it towed to a repair shop. They plugged into the truck and said it was giving code P0016. I had it towed to another place and that it is where it is sitting now. I also received a email from onstar saying "A critical issue with the engine and transmission system in your 2021 GMC sierra Crew Cab has been detected. P0016 was detected. I searched my VIN # and it says that there are no recalls on my truck. I do see that there was a silent recall on the engine that is in my truck.

Filed Jan 15, 2026 · Electrical · MI

Truck went in service 9/17/2025 because the wheels locked up while driving. Transmission was replaced. Picked up truck and 2 hours later the truck shut off while driving and was started back up and was limp mode. Was told wire chaffing and they taped and rerouted wires. Picked truck back up and next day it did the same thing. Took back to the dealer and they said wires again. They taped wires back up and we picked up the truck. We had it 7 days and while driving down the expressway the whole truck shut off and would not start up again. Clearly that is a safety issue. After sitting on the side of the expressway for 10 minutes it started up again and was in limp mode and taken to the dealer again. I don’t know what has been done to it yet as they are not great at communication but they have had our truck for 4 months minus the 7 days we had it before it had to go back to the dealer.

Filed Sep 16, 2025 · Transmission · TX

I have contacted local GMC repair facility (Frank Brown in Lubbock Tx.) about the safety recall on my 6.2 liter engine to attempt to schedule an inspection of my engine and cannot get them to inspect the engine which the recall notice said they would do. They continue to stall and say the inspection isn't approved by GM. I've tried 3 different times to address this isuue without satisfactory results. I recieved the GM safety recall N252494000 notice for my vehicle in May 2025

Filed Jul 24, 2025 · Engine · 48,000 miles · AZ

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle stalled, lost motive power, with smoke came from the engine compartment. There was no warning light illuminated. The vehicle was towed to the residence. The contact attempted to start the vehicle and noticed a knocking sound coming from the engine with the check engine warning light illuminated. The contact received notification of the federal safety agency Campaign Number: 25V274000 (Engine and Engine Cooling). The dealer was contacted and informed the contact that parts were not yet available. The dealer informed the contact that the vehicle had a Salvage Title and would not be repaired under the recall. The manufacturer was made aware of the failure, and a case was opened. The failure mileage was approximately 48,000. VIN tool confirms parts not available.

Filed Jul 11, 2025 · Engine · 70,000 miles · TX

The contact owns a 2021 GMC Sierra 1500. The contact received notification of the federal safety agency Campaign Number: 25V274000(Engine and Engine Cooling); however, the part to do the recall repair was not yet available. The contact stated that while driving at approximately 60 MPH, the check engine warning illuminated and the vehicle stalled. The contact pulled to the side of the road and attempted to restart the vehicle, but the vehicle failed to restart. The vehicle was towed to the residence. The contact stated that the failure had previously occurred several times while driving. An unknown local dealer was contacted and informed the contact that the recall parts were not available. The vehicle was not diagnosed or repaired. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was contacted and a voicemail message was left, but the manufacturer had not returned the contact's call. The failure mileage was approximately 70,000. VIN tool confirms parts not available.