2020 GMC Sierra 1500 Powertrain (other) Problems

"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."

NHTSA ID

11755269

Incident

Jul 31, 2026

My truck shudders when driving. It has 78,000 miles on it. It started shuttering around 73,000 miles. I baby my truck and don't do switch backs or hot rod around.

NHTSA ID

11754596

Incident

Jul 1, 2026

My truck transmission beed jerking off and on for over a year. One time it lose power when i was driving and could have caused an accident. I took it to the dealership and they said i new a new transmission for $12000. Something just doesn’t seem right about this! I brought a brand new truck thats unsafe and its no recall for my model but other models with the same issue had a recall. I would just like some answers. I feel like i brought a lemon. Thanks for listening.

NHTSA ID

11750977

Incident

Jul 2, 2026

The contact owns a 2020 GMC Sierra 1500. The contact stated that upon taking the vehicle to the dealer for a transmission fluid flush and refill, the contact was informed that the transmission was inoperable, and the vehicle could not be driven to the residence. The dealer determined that the torque converter needed to be replaced. The dealer replaced the torque converter and advised the contact to drive over 1,000 miles for the issue to self-correct. The contact stated that the vehicle continued to shudder and drive bumpy while driving after 1,000 miles. The vehicle was taken back to the dealer, where the torque converter was replaced a second time; however, the failure persisted. The dealer informed the contact that the diagnostic test results were sent to the warranty company for the transmission replacement approval. The vehicle was not yet repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 85,165.

NHTSA ID

11745896

Incident

Dec 15, 2025

Mileage

85,165 mi

The contact owns a 2020 GMC Sierra. The contact stated while driving at an undisclosed speed, the transmission hesitated and shifted unusually rough. No warning lights were illuminated. The vehicle was taken to an independent mechanic where it was diagnosed with a transmission valve issue. The contact was advised that the power train software needed to be updated. The contact was informed of an unknown recall; however, the VIN was not associated with a recall related to the failure. The vehicle was not repaired. The dealer was made aware of the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 88,000.

NHTSA ID

11743308

Incident

Jun 9, 2026

Mileage

88,000 mi

Transmission, going towards home up a mild hill, broke top of hill trans shifted to next gear, rear wheels locked up and tires squealed. doing around 40 mph. Took it directly into the shop, and the trans was destroyed inside. broken parts in the pan. Trans could not be repaired, had to get a new transmission. I limped to the dealership, just noisey under vehicle. There was special coverage till 115,000 mile, had 97,062 miles on it. Just like it blew up inside. I was without a vehicle for 5 weeks, but I did have an extended warranty which it paid all of it except $ 1404.01, and I had to pay 2 weeks of car rental for 893.00. The transmission $ 6782.97 , and I would like reimbursement for what I paid. I could only go 10 to 15 mph to the repair shop, which was 7 miles away. GM states it was something else at the dealership, but it was parts all over inside of the pan when they took it apart.

NHTSA ID

11741871

Incident

Feb 11, 2026

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)

NHTSA ID

11740779

Incident

May 28, 2026

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!

NHTSA ID

11734885

Incident

Apr 30, 2026

After owning this truck a little over a year I’ve had to replace the transmission and now it’s in the because the motor sounds like a bag of marbles was put in it and the warranty company is a joke they only want to replace just the cam and lifters but yet the dealership hasn’t be authorized to go to the bottom of the motor to check it out this truck has been nothing but a lemon!!!!!

NHTSA ID

11732880

Incident

Mar 30, 2026

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving on several occasions at various speeds, the vehicle started shaking and slipped in and out of gear, with the message "Idle Transmission" displayed. The vehicle was pulled over and shifted into park(P) and then to drive(D). There was a loud banging sound coming from the rear of the vehicle. The vehicle was towed to an independent mechanic, where it was diagnosed with transmission failure. The contact was informed that the transmission needed to be repaired. The vehicle was not yet repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 80,000.

NHTSA ID

11727414

Incident

Mar 24, 2025

Mileage

80,000 mi

Truck broke down with a rear-wheel lockup and had the transmission replaced in June 2025. In December 2025 and February 2026, truck lost power two times and entered limp mode while on a major highway and major interstate. The problem was misdiagnosed in June 2025, diagnosed properly in December 2025, but not properly repaired, and diagnosed properly in February 2026. All three times the vehicle had this issue, two of the same exact DTCs were present. This is a safety defect, and I have lost all confidence that the vehicle is reliable enough and safe enough for myself and my family.

NHTSA ID

11725751

Incident

Feb 19, 2026

Hi, was driving Vehicle GMC 1500 Denali, vehicle Lost power, all Lites lite up on Dashboard, Vehicle Just lost power and i swerved off Road and sideswiped a Plant Holder on side of Road, damaging side passenger Rear door. I bought the truck to GMC Rvc and they said vehicle Blew Cam shaft and Lifters. I explained to them I'm very concerned for others safety in these Vehicles with the 6.2 Engine. Someone is going to get Killed or even a family. I did look up this vehicle its not listed in Recall, but this vehicle has same engine as ones in Recall. Rvc Gmc issued me a bill for repairs for the amount of $8185.20 and they stated they took 3k off invoice. I did Pay total Invoice....I'm just asking you to please look into this as this is defiantly an issue and this year should be listed on Recall as well.. Thanku for at least looking at this. My cell is [XXX] if you need to reach us...Thx.... INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11722264

Incident

Feb 17, 2026

Vehicle is shifting hard when switching gears. Typical with the recall and the valve body being the issue. Dealership is saying it is not covered by recall.

NHTSA ID

11720842

Incident

Feb 2, 2026

On Friday, January 30, 2026 while driving our 2020 GMC Sierra 1500, we experienced sudden loss of power and the motor making a faint rattling noise. The motor soon after began making a horrible sound - - it was obvious something was very wrong. This vehicle only had 31,995 miles on it at the of the issue. We had the truck towed to the dealer the following day for evaluation. Upon inspection, it was determined that the #5 lifter had collapsed and the left bank of lifters needed to be replaced at an estimated cost of $4500. There were no warning lamps or alerts on our app for over 24 hours. Once at the dealer, we explained to the service advisor that our research concluded that GM is fully aware of these issues and that they are under investigation for possible recall. Our service advisor then made a call to GM who agreed to cover this repair under warranty (which we appreciate and feel was the right thing to do). However, after additional research, we are concerned that the right bank of lifters will fail next, or even worse, catastrophic engine failure that GM will refuse to cover. It is our understanding that NTSB is aware of these issues and is in the process of conducting an investigation. I would like to have our issue added to the investigation.

NHTSA ID

11719423

Incident

Jan 30, 2026

My engine is projecting a ticking sound. Oil consumption is extreme.

NHTSA ID

11718471

Incident

Jan 2, 2026

My 2020 GMC Sierra 1500 experienced a premature transmission failure consistent with GM’s known 8-speed transmission defect. My safety and the safety of others were put at risk if/when the transmission occurs a temporary lockup which can/will cause the vehicle to stall on the highway, and potentially create a minor/major automobile incident if vehicle stalls. The vehicle was taken to dealership Capital Chevrolet Montgomery, AL where dealership technician diagnosed/confirmed the issue along with pictures of internal transmission failed components as well as recommended resolution for fix. The vehicle has been inspected by my out-of-pocket expense extended warranty company Endurance Warranty Services sub-contracted repair claims adjuster. No warning lamps, vehicle messages, or other symptoms of the problem prior to the failure were noticeable; the vehicle had multiple diagnostic scans prior to original sale and after sale to present no issues or trouble scans. the first issue appeared or was noticeable 12/08/2025. GM has refused action by asserting warranty expiration despite widespread knowledge of this defect. The vehicle has been out of service since December 8, 2025.

NHTSA ID

11716407

Incident

Dec 8, 2025

The contact owns a 2020 GMC Sierra 1500. The contact stated that while his wife was driving at an undisclosed speed, the vehicle jerked violently. The driver stated that the vehicle failed to respond as intended while depressing the accelerator or brake pedal. The check engine warning light was illuminated. The driver was able to pull over to the side of the road. The vehicle stopped jerking while driving but failed to exceed 30 MPH. The driver pulled into a parking lot and parked the vehicle. The contact was made aware of the failure and went to the parking lot. The vehicle was restarted and jerked abnormally. Additionally, while shifted into reverse(R), the vehicle failed to function as intended. The vehicle was taken to the dealer, where it was diagnosed, and two DTC were retrieved for unknown transmission software failure, and it was determined an unknown part in the transmission had failed. The dealer informed the contact that an unstated recall was closed. The vehicle remained at the dealer unrepaired. The manufacturer was made aware of the failure, a claim was filed, and the contact was informed that the recall was closed. The failure mileage was approximately 146,000.

NHTSA ID

11709924

Incident

Jan 6, 2026

Mileage

146,000 mi

I was driving my vehicle on the highway when the transmission suddenly gave out with no warning whatsoever. When I say gave out, I mean, it just completely stopped working and was unable to go into any gear. I was luckily able to coast over to the median without an accident occurring, but it was not without much concern or worry as traffic moving on the highway is 70 miles an hour plus and quite full of vehicles .I consider myself lucky that I have extensive driving experience and was able to conduct myself calmly under the circumstances. It was a bit tricky, getting situated though under those circumstances. There was no advanced warning in anyway. no engine lights, no sounds ,nothing. This is a well maintained vehicle. All my service is done by the dealership, and I have never been given any indication that there was something wrong. However,After this happened, I have been researching and found that many of these vehicles with this transmission continue to have this problem. This is not normal wear and tear or normal mechanical failure. I have owned many vehicles and never felt as unsafe as I did in that moment, or had a vehicles transmission fail so abruptly.For me, and the research I have done, I can only hypothesize the materials and engineering involved with this transmission are inherently inferior, completely faulty, and a safety risk/hazard to anyone who owns or operates the vehicle. I consider myself lucky to walk away unscathed, other than the economic price that it is going to incur on my finances for repairs.I would hope that it doesn’t take something serious to happen before someone takes action and conducts a recall of this product. From what I have read and what I have experienced, this is truly an unfortunate accident waiting to happen and it appears nothing is being done. I truly hope that you could take a little more look into this matter. Thank you for your time and energy. I have already contacted the manufacturer and felt ignored.

NHTSA ID

11709671

Incident

Jan 5, 2026

My 2020 GMC Sierra with a 5.3L engine and 78,272 miles on the vehicle, experienced damaged lifters which also resulted in a damaged cam shaft. The total repair bill was $9,208.86. While in the GMC dealership for repair, there were 2 other trucks - same model, same year, same engine - in for the same repair. When searching on-line, I found the recall for the GMC 6.2L engine for similar issues. It is my opinion that the 5.3L engine is experiencing the same types of issues. I have driven GMC trucks for almost 40 years and have never experienced these types of issues. I have been told by several people that it is related to the Dynamic Fuel Management system and to fix the problem to disable the system to keep the truck in V8 mode. There are several solutions on line to make this happen. I am no engineer and only provide this as background information. From my perspective, it is clear that GM has a problem (whatever the root cause) with their 5.3L engines.

NHTSA ID

11709134

Incident

Nov 14, 2025

While driving on the interstate at 70 mph, the transmission began to shudder. It continued the duration of the trip of 90 mins. Following day, the transmission is continuing to shudder and is now shifting hard.

NHTSA ID

11705162

Incident

Dec 14, 2025

MY 2020 5.3 L GMC AT4 IS EXPERIENCING LOSS OF POWER WITH BUCKING & STALLING. CYLINDERS ARE NOT ACTIVATING WHEN CALLED CHECK ENGINE LIGHT IS FLASHING, IT STARTS ROUGH AND MAKES NUMEROUS NOISES AT VARIOUS SPEEDS, AS WELL AS AT IDLE. SO I BROUGHT MY VEHICLE TO MY LOCAL AUTO REPAIR SHOP. OUR MECHANIC FOUND TWO FAILED FUEL INJECTORS AND A FAILED THROTTLE BODY. THEN THE LOUD KNOCKS IN MY BLOCK FAILED AN ACOUSTIC TEST. HE ALSO DETERMINED THE LIFTERS, PUSH RODS AND CAMSHAFT ARE EXPERIENCING EXCESSIVE WEAR. THE AFM SYSTEM HAS FAILED! HE WARNED ME THAT FURTHER USE OF MY MOTOR (WITH ONLY 42K MILES ON IT) WILL CAUSE A CATASTROPHIC FAILURE. MY RESEARCH SHOWS THAT THESE ISSUES ARE BECOMING COMMON OF 5.3 GMC MOTORS. WE SEARCHED THE COUNTRY FOR A REBUILT MOTOR AND FOUND THAT NONE ARE AVAILABLE FOR THE NEXT SEVERAL MONTHS. HOWEVER, I WAS ABLE TO FIND A NEW MOTOR AT MUCH GREATER COST. GMC HAS DECLINED ASSISTANCE AT THIS TIME. MY VEHICLE HAS NO VALUE AS IS, SO I ORDERED THE NEW GM ENGINE. WITHOUT THE DOD SYSTEM, THESE ENGINES WERE DESIGNED TO GO WELL OVER 100,000 MILES. I AM A FAITHFUL GMC OWNER AND NONE OF MY PREVIOUS GMC TRUCKS (2003, 2013, 2015, 2019) HAD SUCH A MAJOR PROBLEM. NOW THE 2020'S FUEL SAVING SYSTEM HAS FAILED AND REQUIRES REPAIRS THAT AMOUNT TO HALF THE VALUE OF MY TRUCK. WHEN A FULL SIZE TRUCK STALLS ON THE HIGHWAY IT'S CERTAINLY LIFE THREATENING.

NHTSA ID

11703015

Incident

Nov 9, 2025

Ticking noise coming from engine slight metallic noise as well. RPMs drop and when they drop, you can feel power loss constant hunting in the RPMs. Also a weird vibration, not all the time in the front end somewhere.

NHTSA ID

11702341

Incident

Oct 15, 2025

-lifter failure on 6.2 v8 engine, causing damage to camshaft -lost significant propulsion while driving on the highway, nearly avoided being rear-ended by another vehicle due to loss of vehicle propulsion -dealer had to to replace lifter bank and camshaft -no issues, once lifter failed dash lights all lit up

NHTSA ID

11701589

Incident

Oct 13, 2023

My truck had engine failure while at the dealership getting new tires installed on 11/12/2025. When they started my truck they detected major knocking in my engine the 1st thing in the morning. It unsafe to drive they're telling me my engine needs to be replaced. My engine has 58,000 miles on it. There was no issues with my truck when I drop it off.

NHTSA ID

11700611

Incident

Nov 12, 2025

First my torque converter went out, no warning lights only shaking wehn shifting, I got it replaced already it cost me $2400 Second Warning light service for Brakes, Traction and power steering come on and off. And sometimes truck doesn't brake well and steering wheel feels hard to drive, it has happened while on expressway with family. Third Engine oil low Add oil warning sign comes up alot and I have to add oil, engine has a rough idle now, also when I turn truck on smoke comes out while having a rough idle, recently it started knocking, I haven't moved the truck since than

NHTSA ID

11699612

Incident

Nov 8, 2025