2020 GMC SIERRA 1500 Engine Problems

6.2L V8 engine in 2020 GMC Sierra 1500 AT4 suffered two lifter failures, which damaged crankshaft and sent metal shards throughout engine and oil. Total engine replacement required. This issue is subject to a recall for 2021 - 2024 model years and the recall should extend to 2020 model years. Vehicle was traded without functioning engine at a significant loss in value for new vehicle, and is not available for inspection. Vehicle was inspected by service department at GMC dealership and traded to a different GMC dealer. No prior indications of problems or warning lights until engine failure occurred while driving.

Engine misfiring and rough idle with occasional flashing engine light. Dealer said no codes to know what to look for despite replicating issue. Eventually it threw a Cylinder 5 misfire and thus GM dealer was able to look further. They found metal in oil pan and concluded a bearing issue and would need to replace engine.

Engine timing chains failed at 71,000 miles requiring a $9,700 repair. Warranty covers 5 yr/ 100k miles and was not fully covered by GM since the vehicle was 9 months beyond 5 years, yet still well within the 100k miles. Issue was diagnosed via P0016-00 being set indicating misalignment between crankshaft position sensor and the intake camshaft position sensor. This issue is a known problem with the early LM2 engines, and the timing chain was upgraded in later LM2 engines. Early adopters of the LM2 are left to pay the price for a defective part.

Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working”

Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working“.

Constant engine issues, cams, lifters. Transmission problems. These engines in these vehicles need to be RECALLED. I have bought 6 of these trucks and all of them have the same issues. SPENDING 14k on new engines one after another is ridiculous. These are classified as “work” trucks and can’t handle “working” 

The engine coolant control valve on my 2020 GMC Sierra 1500 with the LM2 Duramax diesel failed. The failed part is still in my truck, which remains at the dealership awaiting replacement. The repair is delayed due to the part being on nationwide backorder, further highlighting that this is a widespread issue. When the valve failed, the truck entered reduced engine power mode while I was traveling on the interstate. This limited my speed to about 40 mph while climbing a hill. The sudden loss of power in high-speed traffic created a serious safety hazard, as it significantly increased my risk of being rear-ended or involved in a collision with faster-moving vehicles. I drove the truck directly to the dealership after the incident, where the problem was immediately confirmed. The issue was diagnosed and confirmed by the dealership, which identified the coolant control valve as the failed component. To my...

2020 gmc sierra 1500 elevation 5.3l engine. Lifter failure due do faulty design I’m afm/dfm systems.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at various speeds, the vehicle jerked abnormally while depressing the accelerator pedal. A dealer was contacted. The vehicle was taken to the dealer, and the technician informed the contact that the failure might be related to the engine or transmission; however, the contact was informed that the vehicle needed to be inspected to determine the cause of the failure. The vehicle was not repaired. The contact stated that the failure had occurred several times. The manufacturer was notified of the failure and informed the contact to file a complaint with the NHTSA Hotline. The approximate failure mileage was 41,248.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving approximately 40 MPH, there was an abnormal knocking sound coming from the engine compartment. The contact stated that several unknown warning lights were illuminated, and several messages were displayed. The vehicle was driven to the side of the road to safety and turned off. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure milage was approximately 76,000.

The contact owns a 2020 GMC Sierra 1500. The contact stated that on several occasions while the vehicle was started, the check engine, brake system, and another unknown warning light illuminated. Additionally, the messages brake system failure, steering wheel failure, low oil, and two other unknown messages were displayed. The contact also stated that the rear-view camera remained displayed while shifted into drive, and the instrument panel failed to operate as intended. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 65,000.

Vehicle: 2020 GMC Sierra Denali 1500 (VIN: [XXX] ) Description of the Problem: My 2020 GMC Sierra Denali has developed serious engine problems that create unsafe driving conditions. On [XXX], I documented loud knocking and clicking noises coming from the engine. The vehicle also shows warning lights and unpredictable performance. Because of these defects: •I cannot safely drive the truck without risk of engine failure while on the road. •The noises and mechanical issues raise concerns about potential loss of power, stalling, or catastrophic engine damage at highway speeds. •No independent mechanic will touch the vehicle because of the complexity and risk of the defect, leaving me stranded. General Motors has refused to take responsibility, and the BBB AUTO LINE denied my case due to mileage, but the defect itself is unrelated to mileage or normal wear. This is a manufacturer defect that creates a safety hazard for me, my...

My 6.3l v8 Started having a slight misfire while driving. Took vehicle to a mechanic and was advised to change the spark plugs, changed spark plugs, spark plug wires, and ignition coil packs while still experiencing sudden misfires while driving. Starting to consider the 6.2L L87 collapsing cylinder issue.

I have a 2020 sierra 1500 6.2 with 86,000 miles. I have only had this truck 6 months. This was inspected before I purchased with no engine issues. Since purchasing we have driven less than 6000 miles. While driving my vehicle the rod in the engine failed and started knocking. I am a mechanic and I am GMC master certified. Both myself and the owner of the shop I work at diagnosed the vehicle with a bad engine. We looked at the recall for the 6.2 engine and noticed that many of the 2020 vehicles with this engine have the same issue that is currently being recalled for this specific engine. I called GMC and they won’t fix the issue that the vehicle is having. They won’t perform the recall and again I have only had this vehicle for 6 months and with 86,000 miles should not be having this...

For approximately the last year (2024-2025) my 2020 GMC Sierra 1500 AT4 with the 6.2L engine has had noticeable ticking, knocking, and unprovoked shaking upon start up and idle. The pickup has stalled out at stop lights and intersections in the past, posing risk. In June (2025) the pickup was taken to a certified mechanic for inspection who suggested possible lifter or valve failure. The vehicle exhibits a persistent ticking sound from the engine, which I believe may be related to lifter or valve issues, similar to those reported in lawsuits against GM for 2019-2024 models and the recall for 2021-2024 models (NHTSA Recall ID: 24V-676). This ticking occurs regularly, including at approximately 54,500 miles, and raises concerns about potential engine failure or sudden loss of propulsion, which could be hazardous, especially at highway speeds. I have noticed approximately 2 quarts of engine oil usage per my last 2 oil...

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving with cruise control mode set at 55 MPH, the vehicle independently accelerated to 98 MPH, and then the vehicle lost motive power. Additionally, the contact stated that the vehicle had failed to turn off upon pressing the Engine Start/Stop button. No warning light was illuminated. The vehicle was able to restart and was taken to a local dealer to be diagnosed, but the cause of the failure could not be determined. Additionally, the contact noticed that water was leaking inside the vehicle through the rear window on rainy days. The contact stated that the infotainment screen had failed to turn on as intended on some occasions, and the screen had displayed a rearview camera image while the vehicle was in drive(D) on other occasions. The contact stated that while driving at various speeds, the transmission made...

My GMC had a terminal engine failure around 5/3/25. This disengaged the ESC, parking brake, and driver assist abilities as well as making the truck undrivable. GMC service diagnosed the truck needed an entire new engine. The repair took over 2 months to complete and now that I have the truck back, the adaptive cruise control is not working.

Check engine light came on. Cooling fan for engine running none stop. Reduce power mode from engine. Took to dealer, said it’s the coolant control valve. Dealer said the part is on back order and don’t know when they will get it in. Looked up the issues and sounds like many people are having the same problem with the 3L diesel from GMC. These people reporting the same thing and having to wait months for the part. My truck was just out of warranty by 200-300 miles

On June 19th, 2025, I was driving to work when my truck began to lose power, and the check engine light came on. The error on the display is Loss of Engine Power. I took it immediately to Oreilly's so they could run the free engine light check. When they got the report, the employee was amazed that there were over 45 problem codes showing up. As I drive the vehicle there is a pull back from the engine before it starts to pick up speed. On braking as well there is a little kickback before it comes to stop. It takes more foot pressure to pick up speed. The Truck using up more fuel because of this issue. I took the truck to a local certified mechanic, and he ran the diagnostics as well and it came up with the over 45 problem codes as well. His recommendation unfortunately...

Engine overheating at 50,000 miles. Temp would intermittently jump up to 230plus degrees while driving. Radiator replaced per dealership diagnosis. Issue still happening.

Woke up one morning and the entire back seat, entire truck flooring was soaking wet. Got it to Gerber collision in El Reno, Oklahoma. They said that the back window had a crack in it. My insurance said it is a mechanical issue on the sliding back glass and they do not cover such issue. Also want to turn in that the transmission in this truck had to be replaced two week prior to this incident. The truck only had 118,000 miles on it. Safe to say that this 10 point GMC diesel truck is a nightmare and the entire truck is a hazard. They need to take these truck off the market.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving on a main road at 40 MPH, the vehicle lost automotive power, causing the vehicle to shut off. There was no warning light illuminated. The vehicle was towed to a local dealer where the vehicle was diagnosed, and the contact was informed that the engine wiring harness was faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 80,000.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine compartment before the vehicle lost motive power with the check engine warning light illuminated. The vehicle was towed to the residence. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The dealer referred the contact to the manufacturer for further assistance. The manufacturer was made aware of the failure. The approximate failure mileage was 138,000.

I own a 2020 GMC Sierra 1500 with a 5.3 liter engine..... My engine lifters failed at 105,235 miles.... Lifter broke and damaged the Cam Shaft to a point that required full engine replacement costing me $10,800. When I asked GM for help, they denied because I went to a local repair shop with certified mechanics. I believe GM is fully aware of this problem and they are ignoring I think GM should pay for at least half of my repair bill. Thank you!

Engine failure/ lifter issue with no prior warning. Driving down the road vehicle suddenly lost power and error message appeared. The vehicle was inspected by GM dealer and extended warranty company in late 2023. We no longer own this vehicle

I took my 2020 GMC Sierra 1500 to the dealership after Cylinder #5 seized while driving, and I was forced to replace the entire engine. At the time, I contacted the dealer and was told there was no recall related to this issue. However, I have since learned that GMC has issued a recall for similar engine problems affecting 2021–present Sierra 1500 models, but not for my 2020 model year. I believe this issue may be related and would like further investigation and consideration.

My engine slowed down on the interstate. My steering wheel was visibly shaking and I lost the steering access control. The truck threw an Cylinder 6 error code. At the mechanic, they identified that at least one of my camshaft lifters had failed. If I had continued to drive my vehicle, the engine block would have eventually locked up.

Vehicle currently has 104K and needs a 3rd engine. The same issue happened to the second engine as the first. While Driving the engine just stop working. They say it is a problem with the camshaft. Metal gets into the transmission and that also has to be replaced. A vehicle engine should not just stop working! Especially on an interstate. GMC refuses to add this engine to the recall list. However, I don't understand how the safety of families can continue to be placed in jeopardy.

Transmission has slipped and shuddered multiple times. We have had it diagnosed at gmc dealership and our mechanic, advising that it is 8L90 transmission failure. It will slip to lower gear abruptly, causing for possible safety issues especially on the highways.

1. On 05/9/25, the exhaust emissions system malfunctioned, triggering diagnostic trouble code P2C7A (exhaust emissions system failure). This repair, the seventh attempt since June 2024, addressed the same recurring emissions issue previously involving replacements of components such as the NOx converter (02/18/25, 03/13/24) and EGR valve (02/18/25). The vehicle is available for inspection upon request. 2. The P2C7A failure risks limp mode, reducing vehicle power unexpectedly, which is hazardous on highways, especially while towing. Exhaust emissions system malfunctions release excessive pollutants, posing environmental and health risks to others. 3. Yes, the P2C7A code was confirmed by dealer during the 05/9/25 repair, following prior confirmations (e.g., 03/31/25–04/05/25. 4. The vehicle was inspected by Young Chevrolet-Cadillac during multiple repairs (e.g., 03/31/25, 05/9/25). 5. Yes, the check engine light and OnStar emissions alerts appeared prior to the 05/9/25 repair, first noted ~June 2024 (P2C7A onset). Exhaust smell and reduced fuel economy were observed...

Hi I have always taken good care of my 2020 gmc Sierra 1500 at4 6.2 Kept up with its regular and recommended maintenance. I had no warning signs on the dash. So it surprised me that while on my way to work early one morning I was getting off the highway exit and the truck lost power, my steering wheel hardened and it posed a great threat to my life and others on the road, as it suddenly decelerated in a area where people are driving at accelerated speeds. The whole truck was loosing power and shaking hard as I attempted to steer it to a safe location on the side of the road. Had a mechanic inspect it and they determined The truck ended up with a seized engine. I have since not been able to use my truck for 8 months and still currently paying monthly payments of...

Loss of power steering. Loss of engine propulsion at high rates of speed. Engine would not start.

Lifter failure at around 102-103k miles, was doing a random misfire and transmission studder ( due to the dfm system activating, cutting down cylinders to save fuel while driving, this was happening since approx 59k miles, dealership and gm was aware of it and they said it was normal, but that normal misfire turned into a failed lifter causing misfire and studder. I ended up replacing the lifters myself put solid lifters and a new camshaft that would eliminate the dfm system and studder, ran good no studder and random misfire, and now my crankshaft or oil pump is bad which I will remove motor to furthermore inspect. I’ve read forums and stuff where people would get a lifter job done and then soon after couple thousand miles later the motor goes bad. The 5.3 motors have bad crankshafts, oil pump and lifters just like the 6.2lt motors. After the...

Misfire alerts causing major motor repairs

My 5.3 engine spun a bearing on the crank. Same exact problem the 6.2 got recalled for. Now if I put a used engine in it’ll cost me around $6,000.

TRANSMISSION SHURTTING, JERKS, AND VIBRATION, BAD TORQUE CONVERTER BUBBLE AND PELLING PAINT. IT FEEL LIKES ENGINE IS LOSSING POWER

6.2 liter engine fail- replaced at new cost, 20,000 miles later another 6.2 engine failed. unable to get new engine due to GMC finally recalling the engine. My VIN is not included in the recall. I now have no vehicle to drive but still have a loan to pay.

Driving at freeway at 65mph, suddenly is air noise like air conditioning blows air at high fan speed, than the dash info shows (Engine Power is Reduce) try to accelerate to pull out of lanes, and it did not, keep losing speed, as slowly move lanes to the right of freeway, and then exit.. This is the second time of this incident, first time under warranty, dealer fix transmission first time, then two months later, the tansmission was replace wit a newone, now is passed warranty, had the car taken to dealer, they gave me and estimate of more then $10,000 to fix the vehicle, this happen on May 21, 2025...

Vehicle drop in gear / down shift while driving on the highway. went from 75MPH down to 55MPH due to high RPM revs.

Vehicle Stuck in gear. Dealership was delivering the car back to myself when about a mile out from my house when the vehicles made a sudden downshift and was stuck back in gear. Driver called and notified me that it was on its way back to the shop for further work

No warning; picking up child from daycare. went to depart daycare when my dash lit up like a Christmas tree with various errors, alerts, warnings; along with, not being able to start. had to be picked up by spouse and get the truck towed to the dealership for maintenance. Maintenance tech discovered that the grounding straps for the truck needed to be replaced / resulting in a complete electrical failure of the vehicle.

Engine light came on and real bad urine smell / burning coming from the vehicle / rough performance. This issue occurred at various speeds / trips / drive types with the only variation being speed from 25MPH to 75MPH. Vehicle went in to discover that the reductant control module software (RCM) out of date, and two NOx sensor failures

Vehicle was going in for warranty recall; however, i requested they look at the DEF system as my DEF gauge would bounce between full and empty; along with, alert me of going into LIMP mode. GM Maintenance updated the recall and noticed that the DEF tank sensor failed and required to be replaced.

Engine light would come on for a few days and than turn itself off. this occurred for about 8/9 months; however, instructed by the GM Maintenance department that if the vehicle came in and the light turned off before they got to it i would be charged for the diagnosis and no work would be performed. Engine light came on and i was able to park the vehicle / they picked it up and read it prior to putting in their lot until a tech became available. GM Maintenance was able to diagnosis that there was an issue with the EGR sensor and NOx catalytic converter without filter failed / both items replaced

Engine Light came on, performance rough at various speeds / conditions, and smelled like burning and strong urea smell. GM Maintenance identified a failed DEF injector / replaced

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle jerked while accelerating and while coming to a stop. The check engine warning light was illuminated. The vehicle was taken to the dealer, but no cause of failure was found. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 65,000.

Engine started rough idle, reduced power, poor acceleration, ticking and knocking noises, and a check engine light and a few other lights came on the dash. Safety was not a risk at time of incident. Problem has NOT been diagnosed yet BUT have done a ton of research and it’s all leading towards lifter failure/misfire issues. No warning lights or symptoms prior to sudden problems.

This car had lifter motor failure at 135K miles and Transmission failure at 145k miles, the torque converter of this truck is the culprit of many issues as the lifter issues.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while attempting to start the vehicle, the vehicle vibrated abnormally. The engine warning light was illuminated. The contact stated that on another occasion, while driving at an undisclosed speed, there was an abnormal knocking sound coming from the engine. There was no warning light illuminated. The vehicle was towed to the dealer; however, a cause for the failure was not found. The vehicle was not repaired. The failure recurred and the contact stopped driving the vehicle. The manufacturer was not made aware of the failure. The failure mileage was approximately 110,000.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 5 MPH, the vehicle made an abnormal popping sound. The check engine and the ABS warning lights were illuminated. The messages "Parking Brake Service" and "ESC Service" were displayed. Additionally, the contact stated the vehicle experienced a reduced fuel range. The vehicle was taken to the dealer, where it was diagnosed that the lifters had fractured, causing damages to the engine. The dealer determined that the engine needed to be replaced, and the part was ordered. The vehicle was not repaired. The contact related the failure to NHTSA Action Number: PE25001 (Engine, Engine and Engine Cooling). The manufacturer was notified of the failure. The failure mileage was approximately 80,100.