GMC Sierra Complaints (2020)

626 consumer complaints on file.

#11747468June 30, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11745856June 23, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11745896June 23, 2026
POWER TRAIN
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11745292June 19, 2026
ENGINE
• 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
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11745158June 18, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11744588June 16, 2026
ENGINE
The contact owns a 2020 GMC Sierra 1500 Denali. The contact stated that while parking the vehicle, there was an abnormal grinding sound coming from the engine. There was no warning light illuminated. The local dealer was contacted about the failure; however, the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 98,500.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11743308June 10, 2026
POWER TRAIN
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11742790June 8, 2026
ELECTRICAL SYSTEM, ENGINE, STEERING
- THE GROUND STRAP CORRODED AND BROKE APART. YES, I HAVE THE GROUND CABLE THAT FAILED, IF NEEDED FOR INSPECTION. - YES!!! THE TRUCK'S STEERING KEPT GOING IN AND OUT OF MANUAL STEERING AND THE ENGINE REDUCED IN SPEED ALLOWED, AND THEN THE ENGINE CUT OUT ON ME COMPLETELY - WHILE I WAS IN THE MIDDLE OF A BUSY ROAD TRYING TO TURN ONTO A SIDE STREET. THEN THE ENGINE WOULD NOT RESTART. - I HAD THE TRUCK TOWED ON A FLAT BED TO A GMC DEALERSHIP NEARBY. THEY CONFIRMED THE ISSUE WAS THAT THE GROUND STRAP FAILED. THEY REPLACED THE PART AT MY COST, WHICH FIXED THE ISSUES. - YES, THE DEALERSHIP INSPECTED AND CONFIRMED THE ISSUE WAS THE CORRODED AND BROKEN GROUND STRAP. - YES, THERE WERE MANY WARNING MESSAGES THAT STARTED TO APPEAR ABOUT 3-4 DAYS PRIOR TO THE COMPLETE FAILURE OF THE ELECTRICAL SYSTEM. I STARTED SEEING A MESSAGE ABOUT SERVICING THE TRAILER BRAKE SYSTEM, AND ANOTHER ABOUT SERVICING THE SIDE DETECTION SYSTEM. THEN A SERVICE POWER STEERING WARNING AND TO DRIVE WITH CARE. THE CHECK ENGINE LIGHT WAS OFF AND ON OVER THAT TIME. - I CHECKED THE WIRE CONNECTIONS IUNDER MY VEHICLE TO CHECK FOR BROKEN WIRES OR CORROSION. I DID NOT FIND ANY. I THEN CHECKED IF A HARD BATTERY RESET WOULD WORK, BUT IT DID NOT. LASTLY, I BOUGHT A NEW BATTERY TO REPLACE THE EXISTING ONE, EVEN THOUGH THE EXISTING BATTERY HAD NO ISSUES EVEN WHEN TESTED UNDER LOAD. THAT RESOLVED THE ISSUE FOR ABOUT 35 MINUTES THAT NIGHT AND THEN THE NEXT MORNING. AFTER THAT, THE ELECTRICAL SYSTEM FAILED AND THE TRUCK WOULD NOT START. AT THAT POINT I GOT TOWED IN TO THE GMC DEALERSHIP. I HAD TO LEAVE THE TRUCK FOR A WEEKEND, AND THE DEALERSHIP DID NOT COME UP WITH A LOANER, EVEN THOUGH I REQUESTED ONE. I GOT THE TRUCK BACK ON MONDAY AFTERNOON AND EVERYTHING WAS WORKING FINE SINCE THEN. - OVER THAT WEEKEND, I WAS AMAZED TO FIND OUT ABOUT THE BULLETIN GM RELEASED TO COVER ONLY SOME TRUCKS FOR THE ISSUE, BUT NOT OTHERS! MY TRUCK IS STILL NOT COVERED, DESPITE THE OBVIOUS SAFETY ISSUES I EXPERIENCED!!
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11741871June 3, 2026
UNKNOWN OR OTHER, POWER TRAIN
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11741474June 2, 2026
ELECTRICAL SYSTEM
Fire started under passenger side front seat dashboard when rear defrost was turned on.
Crash:
No
Fire:
Yes
Injuries:
0
Deaths:
0
#11740779May 29, 2026
POWER TRAIN, ENGINE, FUEL/PROPULSION SYSTEM
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)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11739911May 25, 2026
ENGINE
My engine suffered an internal catastrophic event, and needs to be replaced
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11739749May 23, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11739758May 23, 2026
ELECTRICAL SYSTEM
2020 GMC sierra 1500 infotainment system including navigation,OnStar and voice command, stoped working on Friday May 15th with no prior warning. These systems are integral for modern safe travel and severely affects the value and driver confidence in the vehicle. It seems to be running mechanically sound but, with some of the communications and information systems not working properly I am unsure how much of the info is incorrect like the clock (which can not be set manually). I have scheduled an appointment with the dealer for June 2nd the earliest date available.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11739135May 20, 2026
STEERING
A known problem with these trucks is ground strap failure. I was driving and all the sudden lost power steering which almost caused an accident. There is a customer satisfaction program N252515590 that covers 2019-2024 trucks but mine was not included in this for some reason. I did have the truck fixed a my cost and was looking to get my money back from GM. I'm not sure if you can help with this but wanted to make a report that is happening with more trucks then they are fixing. If you need any other info from me please let me know
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11738578May 18, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11736973May 11, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11737142May 11, 2026
ENGINE
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)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11736251May 7, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11735414May 3, 2026
ENGINE
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.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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