2020 GMC SIERRA 1500 Fuel/propulsion System Problems

I started to notice changes in performance around 75k miles. Seemed like performance was subpar compared to what was the norm. Seemed to lose some power. Minimal at first, more so just recently around 90k. Oil consumption was starting to accelerate at each oil change at 75k, 80k, 85k, 90k. To the point around 85k and 90k that I would not go over even 1 mile from the 5k threshold without changing the oil. Around 90k I could tell it was not getting any better, deficiencies were accelerating it seemed. At 91k miles I started to hear clicking noises and loss of power, starts were getting rough, bouncing at idle. I stopped driving it, only driving it to the dealership where I brought for a look at it. Will be driving it again for them to do a deeper diagnostic. Many misfires at cylinder 5. PO305 the issue. Showed up around 91k miles on 12/17/25 Now investigation into my model. I see online.

Fuel management system caused a lifter to fail (stuck) which resulted in camshaft damage at 77,611 miles. GM refused to cover the repair, although there is a pending class action lawsuit against GM for this very issue. Truck was repaired at a GM dealership - Sunrise Collierville, TN. Repair costs was approximately $7,000. This occurred during a 2.5 hour road trip which put lives at risk. The truck began to vibrate, and the check engine light came on. There was no other warning before the failure occurred. No police or insurance were involved. This occurred on 9/27/25. It took the dealership 32 days to diagnose and repair the issue. Thanks.

1. The vehicle’s emissions system is malfunctioning, specifically the ECM (Engine Control Module) related to the exhaust emissions system. The diagnostic trouble code is P2C7A, indicating the system is not performing as expected. Key components such as the NOx catalytic converters and diesel particulate filter have been repeatedly replaced, but the issue persists. The vehicle and all replaced components are available for inspection upon request. 2. The malfunctioning emissions system has led to an exhaust leak that allowed exhaust gases to enter the vehicle’s cab. This creates a hazardous environment for both the driver and passengers, exposing them to harmful exhaust fumes. In addition to reduced engine performance, poorer fuel economy, and emissions non-compliance, this exhaust leak poses a serious safety risk by compromising the air quality inside the vehicle. Prolonged operation under these conditions could lead to adverse health effects and further mechanical failures that impact vehicle safety. 3. Yes. The dealership has diagnosed the problem multiple times. The emissions components have been replaced under warranty on two separate occasions. The dealer attributed the fault to fuel quality; however, Fuel distributor debunked these claims. 4. The vehicle has been inspected extensively by the dealership with invoiced repair work replacing key emissions control components. 5. The check engine light and Service Engine Soon (SES) light have been illuminated with the diagnostic code P2C7A since the initial identification of the problem which started 3JUN24

Coolant control valve and engine cooling fan

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

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.

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 changes (roughly every 6,000 miles). I recently had taken the pickup to a local GM dealership where they informed me that I am not longer covered under warranty and the recent recall is not applicable. I was advised to “keep and eye on it, and get a AAA membership”. I am aware of at least 10 class action lawsuits against GM for similar engine issues in vehicles like mine, suggesting a widespread defect. These issues, combined with the potential for engine failure or impaired vehicle control, warrant investigation to ensure driver safety. I have records of the ticking sound and can provide further details if needed. I am willing to cooperate with NHTSA for inspections or further documentation.

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.

I was about 45 miles or so from home on [XXX]. As I left a business my truck went about 100 feet and the engine stopped working . No warning. Truck was towed to a GM dealer in Wilmington Il. It was determined the cause was due to the wiring from the engine ECM that was run over the top of a very sharp plastic mounting bracket for the ECM. The wire had been cut because of the way this was done at the factory. In addition the fuel pump also needed to be replaced . At the time of this, the truck had 39,140 miles on it. I had no warning this was about to happen. No check engine light went on , etc. Most of my route home is on the highway . Had this not happened on a side street , I would have been involved in an accident. I ended up paying $865.42 plus towing for this repair I should not be paying for. The people at the GM dealer told me this has been happening on numerous GM pick up trucks. This is NOT a maintenance issue or an isolated case. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Number 5 cylinder failure. Engined has failed cylinder is scored causing the engine to miss and lock up. The engine which is a 6.2 l87 is now under investigation for a piston failure causing the engine to lockup. The piston and engine issue has been investigated by my local repair shop and I can provide written and bore scope pictures of the failure. Yes the engine light was on the ESC was disabled and needed replaced and the traction control was disabled also the emergency brake was enabled and then failed

recently when starting truck brake message alert comes across on dash reading brake error, and not to drive above 45 miles per hour and brakes are NOT totally operational, meaning brake pedal has alot of play in it to bring truck to a stop. Have to turn off vehicle , sometimes repeatedly before it apparently resets computer system. This has now occurred four times in last five months. Events and dash warning message very similar to recall issued 3/3/20, but listed as "complete" on recall data base. Need to seriously and immediately looked into and corrected!

2020 GMC Sierra Denali – VIN [XXX] On [XXX] while driving the 2020 GMC Sierra to work I noticed a strong gasoline smell inside the cabin. I immediately returned home and parked the truck in the street. Inspecting the driveway where the truck was parked over night, I notice large gasoline spot. The following day I had the truck towed to Boyds Tire & Service center to have the truck inspected. On January 20 Boyds called me and shared the truck had experienced a failure of the High-Pressure Fuel Pump which has been recognized by GM as a recall under N192283991. I called a local GMC dealership about this failure and they stated it would cost $300 to review and would not perform any work under a recall. Also, the dealership stated they could not service the truck for another two weeks, which I cannot be without the truck that long. So, I had Boyds perform the repair the same day. Unfortunately, GM has not listed my truck on this recall. This is the reason for my submittal and request for a full refund of the repair service due to the failed part. This being a very High Risk of Fire and injury and death, I decide to have the repair completed immediately. I have since contacted GM about this incident they will not consider my request for recognizing and reimbursement for service repair. GMC, Case number [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

On January 8th I was driving when my 2020 GMC Sierra 1500 Denali started to misfire as well as several warning lights blinking. I happen to be a couple miles from the dealership I purchased it at so I drove it straight there. A few days later I was notified it was the lifters that went bad and it would cost $5400 plus tax. This is disturbing since I have only had my truck for a little over 4 years with 68,000 miles on it. After researching the problem it appears that its a common issue and I notices a class action lawsuit for this reason. Since it's not recalled currently I'm stuck covering the invoice. Before the problem happened my truck was driving normal and no warning lights came on. This needs to be investigated so the consumer isn't stuck paying for something that is an obvious GM issue .

I had Engine Failure in June 2024 with roughly 50,000 miles. I was getting on I75 North in Auburn Hills, MI, when I heard a loud pop. The vehicle began shaking violently with a loss of engine power warning displayed, loss of oil pressure displayed followed by 2 successive limp mode warning. The vehicle would not drive over 25 MPH. Luckily the next exit was only a mile down the road. I was able to drive on the shoulder of the Interstate to get off of the highway. When I parked the vehicle shortly after, I viewed oil spewed all over the engine bay and under the truck. I then waited 4 hours in 95+ heat for a tow truck. The engine was replaced by the dealer with no root cause identified or communicated to me. There were no warning prior to this failure. The vehicle has had over 13 warranty related issues including the DEF heater melting, CAC pump failure, Numerous Exhaust Leaks, NOX and EGR sensors failing, brake control module faults etc.

GDI fuel pump went bad needed replacement.

Shuttering while in motion at a speed of 35mph or above. My 2020 GMC SIERRA 1500 AT4 CarbonPro while driving at or above speeds of 35mph experiences a hesitation and severe Shuttering while trying to maintain any speed of 35mph or above. The hesitation causes extreme vibrations and hesitation when lifting or applying foot to the accelerator. This happens in any drive mode also with cruise control on or off as well as shifting into low and being in any gear trying to prevent it. It also does this on any road and condition. It feels like a slip in the transmission or torque converter, possibly could be the rear end or variable valve timing as well. And when taking of from a red-light or stop sign it slips as if the truck has lost traction, but it hasn't. This is very dangerous and could be the cause of a serious accident when trying to accelerate. If your traveling at hwy speeds it feels as if the brakes are being applied and the tires are going over a washboard which could cause a collision, tire wear, or driveline damage.

My wiring harness which affects all systems. I was on the Interstate when out of nowhere any and all warning lights came on. The power was cut and rapidly slowed down. I also pulled into traffic and the truck just lost power. The problem was confirmed by dealership. The vehicle was inspected by dealership and wiring harness was the issue. The issues appeared out of nowhere. All the warnings lights came on at once. There has been numerous issues with this part and it’s even recognized by just.

13540028 Fuel Pump Power Control Module Part failed leaving me stranded and had to get a tow. When the failure occurred, vehicle would not crank and there was no forewarning. It worked and then it didn't. The part is on notional backorder and there seems to be a lot of vehicles out there with the same issue and that just with the mechanics\service departments I've contacted that have had the part on backorder for months. So the fail rate seems high and I'm sure others got stuck in a lot worse situation than me. Then GMC continues to produce vehicles with a newer similar part while not producing the same part for like new vehicles. Which will probably only compound the backorder issue when the newer vehicles eventually have the same issue.

Fuel Pump Drive Control Module (Part No. 13540028). This item is a recall on several other vehicles, but not identified on my year/model. On 4 separate occasions over a 3-4 week period, the engine starting running very rough lost power and stalled while traveling down the road (highways, interstate, and a side street). I was finally able to pull a fault code and research the history of this code and this part on several other GMC/Chevy modeled vehicles. The dealer advised I was lucky to find the part because most of them are on backorder due to the recall on other vehicles. The one I got was for a recall, but the customer hadn't returned in time so they sold it to me. I had a repair garage replace the component on Jan 13, 2024, and haven't had any repeat issues. The check engine light did come on each time with a P129F code. It would reset after the vehicle stalled and was powered off for 10-15 minutes and the symptoms would go away. Each time left me lucky to get my vehicle over several lanes and off the side of the road. The date below was the last time it happened. The first time it happened was on Dec 6th and the vehicle started back up in just a minute or two. I still have the old part if it needs to be sent and evaluated to compare with other recalls on the item in other vehicles.

Reference your GM/Chevy recall NHTSA [XXX] , I have a 2020 GMC truck with a failed Fuel Pump Control Module, same part/same part number used in the SUVs. Are you going to recall the trucks also. Lucky for me, mine failed as I pulled into my drive way. Had to have my truck towed to the dealership, 2 days later informed my FPCM was bad, and of course there are no replacement part available. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My vehicle suddenly did not want to start without any warning. I drove my truck and everything was good until I turned it on with the remote and not even a minute after it shut off. I tried turning it back on and it only cranked but would not start. I had a mechanic diagnose it and their computer gave them fuel pump error code. They said it was the fuel pump control module and that they have been getting several GM trucks of the same year having that issue. My truck has less than 36,000 miles on it to have this issue and I have seen that GM has issues with their fuel pump components so I dont understand why they have not recalled them. This is a safety concern because these trucks auto shut off when stopped at red lights and it could randomly shut off and not turn back on leaving someone stranded in the middle of the road without any warning.

The fuel pump module failed according to the dealer at 34000 miles . Car stop while driving. Cranks but no start. After resting it for hours I was able to start. Drive couple of miles about 39000 miles it stops middle of driving and couldn’t start anymore but still cranks

The vehicle shut off while driving. It turns over fine but will not crank. Later cranks but again will shut off and not start. This could get me killed on the interstate. It is pulling trouble code P129F fuel pump power control module. This is a 2020 GMC Sierra AT4 with a 6.2 motor with 80,000 miles on it.