general problems of the 2020 GMC Sierra 1500 - part 1

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

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).

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 inf.

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.

Driving approximately 75mph on a local highway, my engine shut down with no warning, the screen said to shift into neutral to restart but nothing happened so I was stranded along the side of the highway and had to wait 2hrs for a tow truck in the middle of the night and the engine is currently locked up.

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.

I was driving doing about 60 mph. All of a sudden the engine stopped and the truck just coasted. I was able to find a safe spot on the side of the road and pull over. Called a tow truck and had it taken to the gm dealership nearby. The trucks engine was just fixed in October of 2025 for the camshaft and lifter rods. It’s currently in the shop and I’m waiting for the diagnostics.

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.

Engine went into limp mode and engine is no longer good.

On xxx my GMC 6. 2l Sierra 1500 denali engine cutoff in traffic and had to be towed. There was no indications prior to failure. Found out after replacing battery that the 400amp fuse blew and the engine seized. Vehicle was then towed to hendrick Buick GMC dealer in [xxx] for repair. My engine has 49,500 miles but is out of warranty due to time. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Misfire on 2 cylinder, noise on start up diagnostic code p0300 p0302 p050 I was driving home and the engine started making a strange sound, vehicle would could no increase speed normally. The dealership did basic analysis from the onboard computer and did a compression test. Heavy knocking sound on passenger side of the engine. The issue happened on Aug 5th 2026. The issue is due to the afm that causes the lifter to fail and dealership says I need a new engine $15787 or replace cam shaft $14530.

"while driving, the vehicle suddenly experienced a flashing check engine light, an electronic stability control (esc) warning light, and violent steering wheel vibrations. The vehicle suffered a severe loss of power and misfired, creating an immediate traffic hazard. The dealership diagnosed the issue as a catastrophic mechanical lifter failure on the 5. 3l v8 ecotec engine with dynamic fuel management (dfm). Despite the dealer replacing an entire bank of lifters, the engine continues to misfire and vibrate. This premature valvetrain failure at only 36,000 miles is a known design defect that causes sudden engine stalling and disables critical safety features like stability control while the vehicle is in motion, presenting a severe crash risk. ".

I brought my truck into a certified gm dealer for recall work on the ground strap. I left the dealership and multiple lights came on dash: check engine light, service ecs, traction control, service parking brake, steering assist reduced. 7 minutes later the engine began miss firing. The dealer asked me to bring it back to the shop and after some digging they discovered my l87, 6. 2 engine was missing firing in cylinder 5. Now the motor needs to be replaced and gm is not standing behind the repair.

The truck starting making a ticking noise within 24 hours the check engine light was on and it starting shuttering. I got it to the dealership were they informed me of lifters failure, and catastrophic engine failure. Dealer is recommending replacing engine since it's a 2020 and not part of recall.

High pressure fuel pump went at 80k and now on my 2nd transmission under 100k miles this is absolutely absurd.

Piston 5 dropped compression to 120 the rest were 190-200. The engine failed therefore none of my parking assist sensors were working and I backed into a car because the truck was misfiring.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while accelerating from a complete stop on several occasions, an abnormal clicking sound was heard from the engine compartment. The vehicle was taken to the dealer, where it was diagnosed with a failed fan belt pulley. The vehicle was not repaired. Additionally, while parked on one occasion, an abnormal clicking sound and a loud bang were heard from the engine compartment, and the vehicle stalled. The contact attempted to restart the vehicle, but it failed to turn over. The vehicle was taken to the dealer, where a failed valve spring was diagnosed. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 75,127.

My 2020 GMC Sierra 1500 denali with l87 6. 2l v8 suffered a catastrophic, silent seizure at 108,000 miles. Driving at highway speeds, warning light stating shift to neutral and press start, engine completely shut off and would not turn back on. I was in the car with my 3 children about to make a turn across a 4 lane highway. I was able to recognize that there was power loss quickly enough that we were safely within the turn median, and fortunately a "good samaritan" stopped to assist us in getting across the highway into a parking lot. I hate to think what would have happened had this power loss occurred during the turn. There was no warning light, sound or other issue prior to this occurring. The vehicle has been meticulously maintained with all services occurring at my local GMC dealership. We had the truck towed to the dealership who confirmed the engine needs to be replaced.

While driving at night, a low oil pressure warning light illuminated on the dashboard. The following morning, I checked the oil level using the dipstick, which indicated a normal reading. Based on this, I proceeded to drive the vehicle. Shortly after departing, the engine began knocking severely. I immediately stopped and returned home. The vehicle was towed to a GMC dealership for diagnosis. The dealership determined that the engine had experienced catastrophic failure and required complete replacement. I was quoted $11,000 for the repair.

The engine had a critical failure at 49,000 miles. It was replaced under the drivetrain warranty. That came with a 12 month, 12,000 mile warranty. Now I have a second engine failure at 59,000 miles. This will come with only a 12 month 12,000 mile warranty because it is not under recall. Also my transmission is now slipping and they are replacing the valve body. They had my truck for 4 months the first time and one month this time. These are the exact same issues with 2021 - 2025 GMC 6. 2l and 10 speed transmissions. If I the issue had happened 6 months later I would have no warranty. I want a recall on 2020's please.

I again have noticed intermittent pulsing at low to medium speeds. At roughly 1k-2k rpm the engine at or about 10-20 mph is pulsating or hesitating with an obvious pulse which you can see on the tachometer as well (bouncing. ) it seems like there is either a computer, fuel flow or electric issue. Also, at speeds up to the 40 mph range, this is happening as well. Yesterday while towing a small 7'x12' empty dual axle trailer I noticed it again, I occasionally use my trailer to haul small loads up to 4500lbs. This has happened before but this time I decided to notate this on your site, since reading about ongoing problems with the 2020 6. 2l GMC Sierra 1500. I was aware of the other following years, 2021-2024? issues and that is why I purchased this 2020 year model. My truck will be available for inspection when the request is sent to me. Safety was not an issue, I ran my truck most of the day. I have not yet notified my Chevrolet dealer, roger dean, cape coral, FL. My truck has not yet been inspected for this issue. There were not any lights or warnings on display at time of incidents. Thank you, [xxx] [xxx] [xxx] information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Good evening, I want to formally document what happened today regarding my GMC sierra after I brought it to the dealership on Friday morning for transmission concerns that I had already reported. At that visit, the vehicle was inspected, and I was informed that the truck was still safe to drive while waiting for the extended warranty approval for the replacement parts that were needed. Unfortunately, today my family and I experienced a very serious and frightening incident on the expressway. While driving, the truck suddenly lost power, barely moved forward, and began shaking violently. We were placed in a very dangerous situation in traffic and struggled with great difficulty and fear just to make it home safely. Once we arrived home, the vehicle completely shut off and would not restart again. This situation was extremely alarming, especially because I had already reported the transmission problems and trusted the guidance given to me that the vehicle was still drivable. My family’s safety was put at risk, and I need this matter to be treated with urgency and seriousness. Please advise immediately on the next steps regarding the vehicle, towing assistance if necessary, and how this situation will be properly addressed. Thank you.

2020 GMC Sierra 1500 began experiencing a slight knocking sound - mechanic diagnosed as a crankshaft issue. As of last night, 5/10, the truck's knocking sound got extremely loud, the exhaust pipe emitted smoke, and the truck began "bucking. " no warning messages or lamps appeared.

• while driving a loud popping and clicking noise started coming from the engine and the truck started shaking. The vehicle is available for inspection • it was a busy two lane road and I had to continue about 30mph under the speed limit to safely get off the roadway • upon start up the engine clicks and pops with rough idle and the truck shakes. A mechanic looked at it and stated it sounds like a lower rod bearing noise • no further inspections have been done • a service esc warning popped up when the engine started making noise during the incident. The truck had been taken in twice for rough idle and engine noises prior to 100k miles, but the dealership stated that the noise and feel was normal for the 6. 2l engines.

6. 2l v8 engine. 2020 build, GMC Sierra 1500 series. Same engine in the existing recall for 2021-2024 models. Received a call from the service department of the dealership that after changing the oil and restarting the truck to reset the oil change indicator the engine shut down. Assistant service manager, stephen poulson [xxx] ) called and provided information that the engine seized and that the technician cannot manually forward or reverse the engine with a breaker bar. According to the technician, this is indicative of a catastrophic failure consistent with the existing recall. The vehicle is currently at carr vancouver Buick GMC and is available for inspection. Nhtsa has permission of this owner to inspect this vehicle involved if they choose. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Sitting at a red light and when the light turned green, the engine made a noise and lost power while trying to cross the intersection. The check engine light came on along with some other lights. It was then towed to a mechanic and the engine had to be replaced due to failure of the lifters. The mechanic said it is a common issue with the gm 5. 3 engine but unfortunately their has not been a recall.

Complete engine failure with 62,500 miles. Truck appears to have the same problem as the 21-2024 which is currently recalled and engines are being exchanged.

I’m scared to drive my vehicle because of the 6. 2l v8 ongoing engine failures! I believe it to be unsafe for travel never knowing when the engine will fail. Now with over 1 million failures of this engine!.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed 60 miles away from home, the vehicle lost automotive power and stalled. The contact stated that the vehicle started smoking. Several unknown warning lights were illuminated. The vehicle was taken to a local dealer, where it was diagnosed and it was determined that the failure was due to an internal failure with the camshaft and the engine. The vehicle was not repaired. The manufacturer was contacted and referred the contact to the local dealer for assistance. The failure mileage was approximately 167,570.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle decelerated to 30 mph. The check engine warning light was illuminated. The vehicle was taken to a local dealer, where it was diagnosed, and determined that the timing belt needed to be replaced. The part was on back order. The vehicle was not repaired. The contact stated the vehicle previously experienced brake failure, sensor failure, and glow plug failure. The manufacturer was contacted, but no assistance was provided. The bbb referred the contact to the NHTSA hotline to report the failure. The failure mileage was approximately 80,000.

We heard a knocking noise and took the truck to the nearest gm dealership. The engine had to be taken apart. The engine is a l87 6. 2 liter v8. The gm dealership service department diagnosed camshaft damage that caused lifter failure. We have since been informed that gm has known about the failure of this engine for many years. In our case, we were fortunate that the engine did not fail when we were on the expressway. This is a huge safety issue. There were no warning lamps or messages from the vehicle, but we heard the knocking noise. We are facing a minimum of a 10,000 dollar repair and will not feel confident that this engine will not put our safety at risk in the future. We understand that the NHTSA has initiated an engineering analysis regarding this engine for the model years 2019 to 2021. (ea25007). We wanted you to have the information of another dangerous engine failure.

My 2020 GMC sierra 6. 2l (only 46,000 miles which is under warranty mileage criteria), suffered catastrophic engine failure while at 40 miles per hour out of no where and rolled without power for about ~60ft. Power came back on, and I was able to get closer to the dealership but again, lost all power and rolled for about 60ft again right in front of the dealership. The truck died while attempting to make a left turn (in oncoming traffic), it got going again in time to finish the turn. When I pulled into the dealership it pulled code p0016 which is the same code for the 2021-2024 recall currently for the 6. 2l gm engine. I had all oil changes completed on time and can show evidence of them. Other repairs, recalls etc were completed at the GMC dealership. The 2020 sierra 6. 2l should absolutely be included on the gm recall. Same issues as 2021-2024. Funny how 2020's just reached over on time limit for warranty. The repair estimate for my truck is over $13k!!!.

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.

When the truck was idling the dod/afm turned on and disabled a cylinder and now I’m just having codes pop up for cylinder misfires.

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.