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.
2020 GMC Sierra 1500 engine complaints
Page 3 of 10: complaints 41 to 70 of 260, newest first, as owners wrote them.
• 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
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 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!!
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)
My engine suffered an internal catastrophic event, and needs to be replaced
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.
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.
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. the federal safety agency 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)
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.
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.
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 federal safety agency 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.
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!
On 6/27/22 my 2020 gmc sierra 1500 at4 6.2L had lifter failure. The dealer fixed that problem and on 7/1/22 again has lifter failure. The dealer fixed that problem again. On 7/13/22 a third time engine had lifter failure again. I requested they need a different engine to be installed and GM agreed andthey install an L87 2022 engine. This engine seemed weak and not right since it was installed. On 10/13/222i took the vehicle in to the dealer with a complaint of ticking noise from engine area and complaint of shifting hard. The fix the shifting but nothing was wrong with engine according to the dealer. On 3/15/24 the noise are worse and I can smell fuel and noticed white milky residue on the oil cap plus a growling nose coming from engine. Coolant keeps going low and white smoke out the exhaust. The dealer does diagnosis and again nothing is wrong. Now starts the oil consumption testing and me letting the dealer know that I can smell oil and exhaust but they can't. On 8/29/2024 I take truck in for another diagnosis for rattle sounds I'm hearing under the hood from the engine especially when you accelerate. I pay $149.49 for the dealer to find the noise and they tell me they can't find anything, but everyone who has rode in the truck can. On 1/27/2025 I take the vehicle in again and the dealer does the valve cover leaking and replaces that is covered. On 2/3/2025 again vehicle back to dealer cause I can smell antifreeze and burning oil smell. The only thing they found was the muffler had a Lil leak so they wanted me to get it welded which i did and so can smell the oil. On 6/16/2025 I take the vehicle in for oil change and leave to go home then go to work about 95 miles or more and noticed after I parked and was working before I was going to head home there was a huge puddle of oil under the vehicle. I took pics. Found after inspecting my vehicle the oil cap was not in filer tube but instead sitting up on air shelf above radiator. Oil filter was about 3 turns loose.
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 federal safety agency Hotline to report the failure. The failure mileage was approximately 80,000.
Driving on highway, engine light came on with many warning lights. Was just starting on a trip to SC then OH to help father for a surgery. Lifters went bad within fist 5-6k miles on the truck (6.2L) causing other damage to the engine such as bent rods (etc). Dealer repaired all DFM Lifters as there were failures on both sides of the engine, but it still sounds like there are issues internally. It is a 2020 manufactured in 2019, I have not had additional mechanical issues, but I have purposely not driven it as much since I feel that it is not dependable. It currently only has about 27k miles and sounds worse than my 2007 Lexus engine with 180k+ miles. I wanted to fill this out, so you have the data for the engineering investigation.
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!!!
I took my 2020 GMC Sierra in for an oil change. The engine seized when it the technician tried to restart the car. We had it towed to GMC where they confirmed the engine seized. The oil repair shop then replaced the engine and when doing so confirmed the original threw a rod which is the same recall issue that is occurring with the 2021-2024 models. I have since taken the car to GMC for a full inspection and made additional repairs. The vehicle is available for future repairs. My safety and others are at risk as the engine could seize leaving my family stranded or endangering others on the road if the seizure occurs while driving. Yes the vehicle was inspected at the GMC dealership and the shop where the engine was replaced with another L87 engine. there was no warning the engine seized after an oil change.
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.
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!!!!!
While driving on the highway, my engine failed unexpectedly and I had to coast across the highway without power. I had the vehicle towed to a GM dealership, where I was informed the failure was due to a lower-end engine issue and that a full engine replacement was necessary. I am aware of known issues with GM’s 6.2L engines and asked the dealership about the related recall. They acknowledged that the failure I experienced is consistent with the symptoms seen in the defective 6.2L engines. However, they stated that because my truck is a 2020 model, it does not fall within the affected VIN range. I ultimately paid nearly $11,000 for a new engine. Given the nature of the failure and its alignment with known issues, it is difficult to believe this was merely coincidental. I strongly believe the same defect exists in my engine, despite it not being included in the current recall range.
There is a click/ticking noise when vehicle is started. Noise gets louder and faster when accelerating. Have taken vehicle to 2 mechanic shops and been told by both places it is bad lifters and exhaust manifolds. I took this truck in because of loss of power. This issue has put me in unsafe/ dangerous positions on multiple occasions.
The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle went into LIMP Mode, and several unknown warning lights were illuminated. The vehicle lost automotive power. The vehicle was taken to the dealer to be diagnosed. There was a knock coming from the engine, there was fuel injector failure, a heated oxygen sensor control module Bank 1 failure, and fuel system failure. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 134,648.
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
My engine started knocking horribly, I need to get a proper diagnosis but cannot afford to have a shop look at it. I have been building engines my entire life and am certain the rod bearings have failed. The engine has a distinct knock under acceleration, you can hear it clearly when pulling away from a stop sign for example.
The contact owns a 2020 GMC Sierra 1500. The contact stated that the vehicle made an abnormal sound while idling. There was no warning light illuminated. The vehicle was taken to the dealer, where the engine was disassembled, and the dealer determined that the crankshaft and the thrust bearings had failed. The vehicle was repaired. The contact related the failure to the federal safety agency Action Number: EA25007 (Engine, Engine and Engine Cooling). The manufacturer was notified of the failure and partially covered the repair cost. The failure mileage was 60,000.
The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at 65 MPH, the DEF tank failed. The vehicle went into three phases of LIMP Mode and the vehicle unexpectedly decelerated while driving. The DEF system service message was displayed. The vehicle was taken to the local dealer, where it was diagnosed with DEF tank failure, and the tank needed to be replaced, even though the tank was full. The part was on backorder for several weeks. The contact was not provided with a loaner. The vehicle was repaired. The manufacturer was contacted and opened a case, but no additional assistance was provided. The failure mileage was approximately 70,000.
To the best of my knowledge… My 2020 GMC Sierra Denali with a 6.2L engine and 74,000 miles had a complete engine replacement. One lifter on bank 2 was stuck, and the push rod in the cylinder was bent. The engine made a popping noise when starting. I took it to a GM dealership, where they quoted $9,200 to repair the issue or $9,600 for a brand-new engine with a 3-year/100,000-mile warranty. I know there is open recalls for 21’-24’ Models, but I would like some help with mine. This kind of problem shouldn’t happen on a GMC - loaded truck with only 74,000 miles. Thank you!
The 10L80 transmission had a catastrophic failure just outside of the GM warranty. At under 70K miles the pump gears came apart and sent metallic debris throughout the entire transmission and exhaust gaskets converter next to the transmission. These will need to be replaced. I have found multiple cases online with this 10L80 transmission where there has been significant problems with these transmissions blowing up or even causing momentary lockup with the wheels. This transmission is notorious for problems but has not yet been recalled. My mom and nephews were in the vehicle when it broke down putting their safety at risk on the the highway. This problem was confirmed by the GMC dealership here in Ruston, LA. The dealership has done the mechanical inspection. The engine started making an extremely loud noise and the warning lights did not even come on until I attempted to start it later after the breakdown.
The contact owns a 2020 GMC Sierra 1500. The contact stated that while starting the vehicle, the engine hesitated while turning over. The vehicle started with the check engine warning light illuminated, and the DEF (Diesel Exhaust Fluid) sensor light was illuminated. The message “94 miles before vehicle enters LIMP Mode" was displayed and instructed the contact to see the Diesel Exhaust Fluid section of the Owner's Manual. The vehicle was restricted to a 65 MPH max speed. The vehicle was towed to a dealer, where it was diagnosed, and it was determined that the DEF tank pump assembly had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 121,000.
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