2021 GMC Sierra 1500: won't start

Filed Oct 12, 2026 · Engine · OH

While towing a trailer on 6/26/26, the 6.2L L87 engine suffered a sudden drop in oil pressure, began knocking, and completely lost motive power on the roadway. Because the engine seized instantly, the vehicle experienced a sudden loss of power steering and power braking while managing the extreme weight of a trailer. This combination created a severe and immediate safety hazard, forcing me to maneuver a heavy, unpowered truck and trailer combination through active traffic to the shoulder without full steering or brake control, putting my life, my passengers' lives, and the safety of surrounding motorists at extreme risk. My dad read the codes before we took it to my mechanics and the only code I can remember is P0016. I took it and dropped it off at my local mechanics on 6/28/26. This is what my mechanic said: No Start-Truck came in not running. Had timing codes. I believe the crank bearing failed causing the engine to lose oil pressure. With the sudden loss of oil pressure, the timing chain tensioner slacked and caused the cam/crank to go out of time. Drained engine oil and found bearing material. We also cut oil filter open and found more bearing material. The timing cover was removed and verified the cam timing was off. In conclusion the engine has failed and will need full replacement. This is the exact failure mechanism under active the federal safety agency Investigation EA26005.

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 Sep 9, 2026 · Engine · IL

Engine I believe The truck died while I was doing 78 MPH on the highway Dashboard stated “shift into neutral and press start” I pulled to the side of the road and did what it stated and it would not crank over. I also put it in park turned the vehicle off and back on to try to start it. The lights on the dashboard, all gauges, the AC, and everything works the truck just will not crank over. Check engine light came on but is not throwing any codes

Filed Aug 21, 2026 · Engine · IN

I purchased this truck from a used car dealer. It had received the fix in January this year. They sold it to me I put 15,000.00 down and financed 15,000.00. I had the truck two weeks and was driving down the road to pick up some tools from a friends. I pulled from a drive way I heard a pop likei hit something In The road nothing was in the drive or road I could have hit. I made it two stop signs to make the turn too go pick up the tools and as I am slowing down to stop the stuck shuts off at like 45 miles an hour and leaves me comming to a stop with a truck crank crank crank no start. Cause it said shift I to neutral to restart. I did and the engine went to cranking over and o er really fast. And I was Abel to get control and get stopped at stop sign blocking the stop sign and a guy with a boat behind me. My friend came with his truck and pulled me from intersection up into His yard. And I had car lot I bought it from come get it they tried to finance me a motor thru there prefers dealer. I went to them they explained that the cams and timing chain was staying still as they turned the engine Over by hand. The timing chain stayed staionary. I researched the truck online figured out there is a l87 recall and had it taken to dealer they are offering good will payment on labor because it is 6, 000 miles past the 150000 dead line Wich I only placed just over a thousand of the 156000 miles on this truck. I have been without this truck for 31 days as of today. And I feel they should replace entire engine. I Am so frustrated with this cause I already payed 15000 and don’t have the money to fix this truck.

Filed Jun 16, 2026 · Electrical, Fuel system · TX

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?

Filed May 25, 2026 · Electrical, Fuel system · SC

My truck will not start when I press the push-button ignition. After waiting a few seconds and trying multiple times, it typically starts on the third attempt. Additionally, it will not restart after the auto stop feature activates at stop signs or traffic lights. This is very concerning, especially when pulling into oncoming traffic, as I’m worried the truck could shut off while I’m crossing. I have already had the battery, starter, and alternator checked, and all components tested fine. However, the issue is still occurring. There are also no warning lights or messages displayed on the dashboard.

Filed Mar 10, 2026 · Electrical, Engine · MO

Following the remedy of the engine recall in 2025, the truck started having intermittent electrical issues (i.e. warning lights on dash turn on/off: service 4WD, Loss traction Control, etc) come one while the truck is being driven. If the truck is turned off while the dash warning lights are on, it will NOT Start for about 24 hours. If the warning lights are ignored, eventually they will go off on their own. Additionally, the truck is having "no-start" problems (randomly the truck does not start, then after a few days it starts). A New development, when backing up there is a scraping/squealing sound (possibly universal joint). Truck has been back to the dealership that replaced the engine block for the recall and they have failed to identify any issues as these problems are intermittent. Engine Recall Replacement Invoice (Attached)

Filed Mar 8, 2026 · Engine, Transmission · AR

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.

Filed Feb 4, 2026 · Engine · NY

Loss of power code p0016 now truck won't start

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 Dec 16, 2025 · Engine · AL

mechanical and electrical issues with my GMC Sierra Elevation Duramax Diesel, purchased in 2021. Despite multiple dealership visits, diagnostic evaluations, repairs, and software updates, these issues persist and have significantly impacted the reliability and safety of the vehicle. In December 2025, my vehicle was taken to the dealership for diagnostics and a third software update intended to resolve recurring engine-related faults. Throughout 2025, the check engine light illuminated on approximately 30 occasions, confirmed by at-home diagnostic scans. The same diagnostic code related to the 1) SCR NOx Catalyst Efficiency Below Threshold Bank 1 Catalyst 2 P2C7A - Engine I 2) Exhaust Gas Recirculation (EGR) Cooler Efficiency Below Threshold P14D9 - Engine has appeared repeatedly since the vehicle was first purchased in 2021. Additionally, on approximately 15 occasions in 2025, the vehicle failed to start. When pressing the ignition button, the engine screeched while attempting to turn over for 20 to 45 seconds, after which the vehicle powered off entirely. After waiting approximately 10 minutes, the vehicle would then start normally. Notably, during these no-start events, no check engine light or diagnostic code appeared, and the engine light and starting failure have never occurred simultaneously. hese same concerns were explicitly explained to service technicians during the most recent recall repair in 2025. I was informed that a software update would resolve the issue. However, the problems have continued. A similar frequency of failures occurred throughout 2024. At that time, GMC advised that the issue was likely the vehicle’s battery. Acting on this recommendation, I had the battery replaced at my expense in October 2024 by the dealership. This repair did not resolve the issue. From the time of purchase in 2021 through January 2024, these same symptoms occurred approximately 10 times, demonstrating a long-standing and unresolved defect.

Filed Apr 28, 2025 · Engine, Fuel system · LA

Motor seized up while going around 65mph. Truck lost all power and would not start brought to dealer and they said that it was the crankshaft bearings and something with the connecting rods, the deal told me that they don’t know what to do and is waiting on GM. There is a recall for these issues but no fix. I’m just waiting for the dealer to tell me what’s next but they don’t even know.