2020 GMC SIERRA 1500 Safety Overview

Component: ELECTRICAL SYSTEM

"The contact owns a 2020 GMC Sierra 1500. The contact stated that the vehicle failed to start intermittently and needed to be jumpstarted. The vehicle was taken to the dealer, and it was determined that there was corrosion on the ground wire which caused the failure. The vehicle was not repaired because the vehicle was not included in Customer Satisfaction Program: N252515590 with NHTSA ID Number: 11027795 (Electrical System) for the ground wire replacement. The manufacturer was informed of the failure and confirmed that the vehicle was not covered. The manufacturer referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 51,000."

Component: ENGINE AND ENGINE COOLING,ENGINE

"The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving 74 MPH, the vehicle made a loud banging sound, reduced engine power, and was losing oil pressure. The dealer associated the failure with NHTSA Action Number: EA25007 (Engine, Engine and Engine Cooling). The dealer was contacted and the vehicle was diagnosed with rod bearing failure. The manufacturer was contacted by phone and made aware of the failure. The failure mileage was approximately 124,000."

Component: ENGINE

"While driving down interstate noticed drop in oil pressure and immediately a noise in engine with loss of power. immediately took it to dealership and they diagnosed rod bearing failure. Gm refuses to pay for engine."

Component: POWER TRAIN,VEHICLE SPEED CONTROL

"The vehicle in questions was purchased with less than 5 miles in year 2020. This vehicle was dropped off at MAC HAIK CHEVOLET MADISON MS on September 25, 2026. I was advised on September 28, 2026, that the vehicle was test driven with the scan tool connected, Graph Torque converter slip, found over 100 RPM slip when torque converter engaged and causing shutter at highway speeds, also felt 1-2 and 2-1 harsh downshift, check fluid condition was black and smelled burnt, replace transmission assembly, flush cooler, program transmission control module and perform clutch fast learn. Estimated cost of $8k"

Component: ENGINE

"Timing in engine is going out at 150,000 miles"

Component: ENGINE

"I was driving on the highway at 70mph when out of no where my truck stopped running and I received a message warning to put the truck in neutral and restart the engine. It was very alarming being on the highway and this happening. I was unable to restart the vehicle so I had to coast and navigate us at high speed to the should of the highway. Since it was Labor day I had to sit for over 4 hours before getting a tow vehicle at 2am to tow my truck to [XXX] FLOW Buick GMC. They contacted me and told me that my engine had seized and that it was possible bearings or something that made it seize and I need a whole new engine. They quoted me 12,500. I have not done anything yet in repairs and I now contacted GM and submitted a Case #XXX. I notified them I am aware of the known issue and the GM service bulletin PIP5900. I am waiting for them to respond now. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: POWER TRAIN,ENGINE

"Powertrain issues and a chassis issue that is extremely dangerous.Tailgate on rare occasions falls open by itself. There is a design flaw in the placement of the catalytic converters. The heat is burning up the fluid. I could not believe my eyes when I serviced the transmission. This is another shortcut by GM to save on the extra wiring needed for the oxygen sensors (2)in the converters and the two oxygen sensors downstream of the converters. There is plenty of room for the converters further down by the tail shaft to drive shaft connections. This is GM’s way of being cheap. Here’s the problem. The converters get way too hot. The fill plug for the transmission which is behind a low rent heat shield crumbled into my hands from excessive heat buildup. GM knows there is a problem with the fluid breaking down. Their bandaid answer is to use Mobil 1 fluid instead of the recommended Dexron 6. What needs to happen is a safety recall issued for the unwanted tailgate deploying all by itself. There needs to be a redesign in the exhaust system. The Transmission (8 Speed) has a catalytic converter exactly on both sides and the crossover pipe runs directly under the transmission sump pan. No wonder they are having issues with transmissions burning up. THIS IS A FIRE HAZARD !!! With the converters being so close to the exhaust manifolds, a leak from the engine or the transmission would be enough to ignite and possibly kill the occupants. All in the name of saving a few cents in wiring. Myself, I am a retired GM Mechanic. I started working at Sewell Cadillac in [XXX] in 1975. I have held the title of ASE Master Tech. Cadillac Master Tech. I have been a GM Shop Foreman and A GM Service and Parts Director in my Career. I retired from Federal Express as in charge of Fleet Maintenance and GSE(Aircraft Equipment). I have certifications from Mercedes, BMW, Toyota, Commander Loaders, Goodyear, and more. Given the right set of circumstances, it could end very badly. Dangerous Truck ! INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)"

Component: ENGINE

"My 2020 GMC Sierra 1500 SLT with the 6.2L L87 engine experienced complete engine failure at approximately 129,000 miles. The vehicle is currently at Trent Cadillac GMC in New Bern, NC and is available for inspection upon request. The dealer confirmed the engine requires replacement along with timing-chain-related repairs, estimated at approximately $11,000. Before the failure, I had previously reported concerns involving oil pressure/engine operation to a Chevrolet dealer. At one visit, the dealer documented that it could not duplicate the oil-pressure concern. The vehicle was later serviced again, but the problem ultimately progressed to complete engine failure. When the truck arrived at Trent after the failure, no oil registered on the dipstick. This presents a safety concern because sudden engine failure and loss of power can leave a driver unable to maintain normal vehicle operation or safely exit traffic, particularly at highway speeds. After the failure, the truck was evaluated by Big Boys in Grimesland, NC and then towed to Trent Cadillac GMC for authorized GM dealer diagnosis. GM Customer Care has also reviewed my case. I am concerned this failure may be related to known failure patterns involving GM 6.2L L87 engines and internal engine components. Although my 2020 model is outside the current recall population, it experienced complete engine failure after earlier oil-pressure concerns. I am requesting this failure be documented and evaluated as a potential safety defect, including whether earlier-model L87 engines may experience similar failure mechanisms."

Component: SERVICE BRAKES,ENGINE

"Lifter failed due to AFM system. Cyl 8 misfire due to oil fouling. The onboard computer got confused and would not release the parking brake until repeated attemtps to release it. 5.3L V8 2020 model year 115250 miles. Isn't this the same problem as the 2021 and newer engines? 8spd transmission. AFM failure. 9k repair."

Component: ENGINE

"While slowly accelerating from a stop, with 4 family members in the truck, the engine began to run rough for about 1-2 seconds then multiple notifications flashed across the dashboard (Check Engine, Steering Assist is Reduced-Drive with Care, Service ESC, and Service Parking Brake). The road we were on was steep and twisty and did not have room to pull over which put us in an unsafe position with compromised steering and no shoulder. We made it 2 miles home but there was smoke coming from the exhaust and the engine ran very rough. Truck was towed to my mechanic. Mechanic confirmed issue. Diagnosis was misfire in #5 cylinder, confirmed initial compression upon startup (1 second) then compression loss and cylinder full of oil due to failed lifter. No previous issues prior to failure."

Component: ENGINE

"I was driving home with my wife. The engine just cut off. No power to the gas pedal. Luckily we were able to coast long enough to find a shoulder to pull off onto. Truck wouldn’t restart. Had to call a tow truck and have it towed to the Chevy dealership. The engine was already repaired once. Ref number 11696129. I just got the truck back and fixed again. So far I’ve had to pay for 2 tows and 2 repairs costing be about 3000 dollars. Both repairs have been done at a Chevy dealership."

Component: ENGINE

"I have a 2020 GMC Sierra 1500 AT4 with the L87 6.2L V8. The cam shaft and lifters have failed for a 2nd time. The first time happened in 2022. It was under warranty and happened at approximately 40,000 miles. This last time it happened in 2026 and was at 125,000 miles - both for the same thing - cam shaft and lifters. Both were sudden failures and luckily I was on a highway that wasn't buy at the time. This time it is costing me $10,000 to fix. They have had the truck for two months now. My understanding is the significant recall that occurred was being investigated to see if it should be expanded. I believe it should have been expanded. Whatever came of that decision? GM told me they could offer no help as my truck was out of warranty and my truck was not on the recall list. I'm curious if it will be expanded and what would happen in my situation if it is expanded. GM has deleted the support message chain that went on for four weeks where I was trying to get them to cover it under the recall and/or explaining the entire situation. Thanks, Brian Hickey"

Component: ENGINE

"2020 GMC Sierra 1500 AT4, 3.0L LM2 Duramax. In service 08/13/2020. Five glow plug failures on five different cylinders in under 19,000 miles, all at one GM dealer, all part 24000504: Cyl 1, 10/21/2024, 38,650 mi, P0671, RO 13714, warranty. Cyl 6, 11/05/2024, 38,793 mi, P1330, RO 26665, warranty. Cyl 4, 11/29/2024, 39,683 mi, P133B, RO 57498, warranty. Cyl 3, 01/22/2026, 52,959 mi, P0673/P06C7/P133A, RO 100951, I paid $713.38. Cyl 2, 08/26/2026, 57,466 mi, P06C6/P0672/P1339, RO 115953, GM under N232430460. The first three came within 39 days and 1,033 miles. Every RO documents the same finding: high internal resistance in the plug, circuit tests good. The failure is internal to the plug. Glow plug failure on a diesel causes hard starting, extended cranking, no-start in cold weather, and startup misfire - risk of being stranded or unable to start. GM has documented this defect three times: PIP5762 (12/2020), TSB 22-NA-027 (2/2022), Special Coverage N232430460 (1/2024). All name an inadequate camshaft housing cover baffle plate weld, and all limit the remedy to cylinder 2. On the recorded walkaround for RO 115953 the tech stated my engine serial falls inside the affected population and my earlier failures were probably the same condition. GM replaced only the glow plug. The camshaft cover GM identifies as the cause is still installed; GM quoted me $5,100 to replace it at my expense. Four of five failures were on cylinders 1, 3, 4 and 6, outside that scope. If the bad weld passes oil into the PCV and intake path rather than only the cylinder 2 glow plug well, ingested oil would reach other cylinders. No RO shows anyone inspected the intake tract, charge piping, cooler, PCV separator, a removed plug, or a glow plug well. I ask ODI to examine whether the cylinder-2-only scope of N232430460 is under-inclusive, whether replacing the plug while leaving the cause installed is an adequate remedy, and whether repeated internal failure of part 24000504 warrants a recall."

Component: LATCHES/LOCKS/LINKAGES

"The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving 45 MPH, the tailgate opened unexpectedly after inclement weather or after the vehicle was washed. There was water and rust found inside the tailgate release button, and the message "Tailgate Open" was displayed. The contact associated the failure with Customer Satisfaction Program: N232426401. The manufacturer was notified of the failure. The failure mileage was 29,000."

Component: POWER TRAIN

"Transmission shifting hard in first few gears and only 87,000 miles on Transmission."

Component: UNKNOWN OR OTHER,ENGINE,FUEL/PROPULSION SYSTEM

"Vehicle: 2020 GMC Sierra 1500 SLT VIN: 3GTU9DEL5LG340438 Engine: 6.2L V8, RPO L87 Mileage: approximately 129,854 miles My 2020 GMC Sierra 1500 equipped with the L87 6.2L V8 experienced an engine failure and has been diagnosed as needing an engine replacement. I am reporting this because my vehicle is equipped with the same L87 6.2L engine currently being investigated by NHTSA under Engineering Analysis EA25007 for engine failures occurring outside the scope of Recall 25V-274. My model year is not currently included in Recall 25V-274. However, EA25007 specifically addresses L87 engine failures occurring outside the existing recall population, including 2019–2024 GMC Sierra 1500 vehicles. GM also issued Preliminary Information bulletin PIP5900, “Diagnostic Tips for Seized Engine or Engine Noise,” applicable to 2019–2023 GMC Sierra vehicles equipped with the 6.2L L87 engine, which identifies possible crankshaft bearing failure. I am requesting that this engine failure be documented as part of NHTSA's ongoing investigation of L87 engine failures outside Recall 25V-274."

Component: ENGINE AND ENGINE COOLING

"The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving approximately 55 MPH, the vehicle started losing power and decelerated. The check engine warning light was flashing with several unknown messages displayed. The vehicle was parked on the side of the road and later towed to the local dealer to be diagnosed. The contact was informed that the lifters, push rods, and camshaft had failed and needed to be replaced. The lifters, push rods, and camshaft were replaced, and the vehicle was repaired. The contact stated that approximately 6,900 miles later, the failure reoccurred. The vehicle was towed back to the local dealer, and the contact was informed that the engine crankshaft and connecting rods had failed and the engine needed to be replaced. The vehicle was not yet repaired. The failure mileage was 115,000."

Component: ENGINE

"The engine blew up driving down the road 5k miles past warranty. Complete junk and had to pay for a new one. They would only put in another defective 6.2 gmc engine and it will fail again"

Component: POWER TRAIN,ELECTRICAL SYSTEM,ENGINE

"5/5/25 woke up back seat entire truck flooring soaking wet back glass cracked. 4/8/25 transmission went out 117,000 miles 7/3/25 exhaust leak and placed nox 1. 7/8/25 127551 mileage exhaust leak replace gaskets, belt , tensioner, and pulley, 6/8/2025 3 knock sensors replaced and replaced intake manifold."

Component: ELECTRICAL SYSTEM,ENGINE

"6 months after owning it the lifters went bad got them Fixed then they immediately went bad again also bent rods then a day after getting that fixed again the oil pump went bad it was issue after issue"