2020 GMC Sierra 2500

76 complaints on file, page 1 of 4.

1. Filed Sep 24, 2026Failure Aug 1, 2025Virgie, KYPower train

   A dealer "fixed" the P20EE code on this date, then the code came back a week later. Same dealer said they don't have qualified diesel technician, took vehicle to a 2nd dealer 9/22/2025, unable to determine cause of code. On 6/18/2026 same P20EE code came on again, took to dealer, dealer able to perform repairs on 7/30/2026 after ordering the correct parts. No on 9/23/2026 P20EE code is back.

   NHTSA complaint 11766667
2. Filed Sep 19, 2026Failure Sep 17, 2026Concordia, KSAutomatic emergency braking, Power train, Vehicle speed control

   While driving vehicle flashed engine power reduction signal and then the emergency brake automatic feature came on abruptly. Fortunately, I had been able to slow down after the reduced power, but if I wouldn't have quickly reacted to that, I think the emergency brake system would have caused a safety issue. Now. The vehicle is incapacitated. There were two recalls that describe this exact situation on the same year and model of truck, but my VIN number did not fall. Under that recall. The recall was for the sensor and then the second recall was because the first recall didn't correctly fix it. But the details of the faulty sensor are exactly what happened to my truck. So it sounds to me like they had more problems than just the recall that they acknowledged but they have not expanded it. My quest is to have them expand the recall to all of the vehicles that had the same problem.

   NHTSA complaint 11765548
3. Filed Sep 5, 2026Failure Aug 24, 2026Fayetteville, NCElectrical system

   When I try to start my truck it comes up as service trailer brake control module and it has caused my truck battery to drain so I cant even crank my truck up.

   NHTSA complaint 11762323
4. Filed Jun 30, 2026Failure May 30, 2025100,000 milesLake Charles, LAEngine and engine cooling

   The contact owns a 2020 GMC Sierra 2500. The contact stated that the check engine warning light was illuminated, and the message "Reduced Power" was displayed. The vehicle was taken to the dealer, where the turbo actuator and wastegate position sensor A-circuit were replaced; however, the failure persisted. The vehicle was taken back to the dealer, and the contact was advised that another diagnostic test was needed. The contact declined to pay for the diagnostic test. The vehicle was taken to a retired GM mechanic, who diagnosed the vehicle with turbo charger failure. The vehicle was not repaired due to the cost. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 100,000.

   NHTSA complaint 11747347
5. Filed Mar 10, 2026Failure Feb 18, 2026Stephens City, VAPower train

   While driving down a highway doing between 45 and 55 mph the transmission suddenly and completely faulted causing the truck to come to a complete stop. Just enough power to get to the shoulder luckily. The transmission had basically completely blown out, fluid everywhere. The insurance company did not find any comprehensive damage. The entire transmission needs to be replaced. There were no indicators showing any problems, no alerts, no warning whatsoever. Mechanics said there was a lot of metal coming out of the transmission. The truck is currently in a mechanic shop awaiting the new transmission, so at this time it is available for inspection. The safety issue here is that it happened on a busy highway, and the vehicle was no longer drivable so it needed to be towed causing more time spent on the side of the road.

   NHTSA complaint 11723197
6. Filed Feb 15, 2026Failure Jan 30, 2026Aberdeen, MSPower train

   A couple times I heard loud clanking coming from rear brakes. One time in particular I was trying to stop and it felt line someone had ran into my truck but must have been the rear wheel locking up

   NHTSA complaint 11718162
7. Filed Dec 20, 2025Failure Dec 19, 2025Noblesville, INElectrical system, Warnings, Service brakes

   The main tailgate will not go down or function properly and it says online there is a national recall for this, but does not come up when I search my vehicle. When I turn on my left turn signal the brights flash for no reason and this is a known major issue with the vehicles as well. The trucks computer is telling me low on coolant even though it is not that has already been fixed through a 3rd pARTY WARRANTY Parking brake was stuck on when I bought the vehicle and had been for a long time you could tell and I had to pay over $1100 to fix it at GM. The Ford collision system does not work properly and the cameras will come on at certain times when they're not supposed to be and not come on when they are supposed to be

   NHTSA complaint 11706292
8. Filed Dec 13, 2025Failure Nov 1, 2025Finleyville, PASteering

   Bad vibration and bad wobble in steering wheel and front end components. This is the 3rd or 4th time my truck has been back to the dealer because of the same issue!

   NHTSA complaint 11704835
9. Filed Dec 7, 2025Failure Nov 26, 2025Three Rivers, CAEngine

   Catastrophic engine failure after taking it in for the April 2025 recall. Complete engine replacement needed

   NHTSA complaint 11703546
10. Filed Nov 24, 2025Failure Nov 23, 2025Gainesville, GAElectrical system, Body, Visibility/wiperFire

    The rear defroster massively overheated. It started heavily smoking and eventually exploded the rear windows. Only warning sign was the smoke which we noticed quickly because the windows were up. Had the windows been down we might not have noticed before a fire started. I'm taking it to a dealership now. This module also triggers on from a remote start. Extremely dangerous!!!

    NHTSA complaint 11701143
11. Filed Oct 14, 2025Failure Jun 13, 2025Sunset, SCPower train

    Torque converter in my transmission we out, causing my gears to grind and lose power. Slight rumbling sound under the front passenger seat, First dealer (Palmen Motors, Kenosha WI) told me there was nothing wrong with the vehicle and no transmission error codes exist. Second dealer (Parks GMC, Greenville SC) indicated that i need a complete new transmission. Part is on backorder for the last 4 weeks and I am without my vehicle. No ETA for new part or any information on why it failed prematurely.

    NHTSA complaint 11693346
12. Filed Oct 7, 2025Failure Dec 31, 1969El Dorado, ARElectrical system, Exterior lighting, Steering

    I have taken the vehicle to my local dealership six times. The tailgate started opening and the headlights were blinking on and off. This happened 3 months after I bought it. The dealership told me they changed the tailgate switch and they said there wasn’t anything wrong with my lights. Two weeks after the dealership said they changed the tailgate switch, the tailgate started opening and closing. The lights also stopped working driving down the road at night. This happened 3 different times at night. The tailgate opened when I was pulling a trailer and it caved in and I had to pay to have it repaired. The dealership said it wasn’t their problem. During this time the power steering fluid was leaking under my steering wheel and ruined my carpet. The dealership has yet to acknowledge that problem. I still have to put power steering fluid in the truck every week and my interior is ruined. The tailgate is still opening on its own. I had to start charging my batteries up every morning because they were dead. I got up one morning and the batteries were dead and the truck wouldn’t start. I had to buy a new $300 key. Took it back to the dealership for an appointment. The truck sat there for a week and I called for an update and they didn’t even remember the truck was there. It still sat there 4 days after that. They told me the truck needs new batteries and it wasn’t under warranty. I spent $1000 on 2 batteries. Tailgate is still going down. The lights are still going on and off. And then the lights and the locks will go on and off while the truck is parked and turned off. And now the new batteries are becoming weak and I am having to get the truck jumped off several times. I have had the truck at the dealership 6 times and they still haven’t fixed anything. When they have my truck I am losing money because I am a business owner and I use my truck for work. I lost all of my tools. I have lost time and money because the dealer has yet to help and do their job. I need help GM

    NHTSA complaint 11691983
13. Filed Sep 15, 2025Failure Jun 11, 2025Perry, MIEngine

    The catalytic converter failed at 93,000 miles, and 64 months. GM says it is out of warranty.

    NHTSA complaint 11687414
14. Filed Aug 11, 2025Failure Jul 11, 2025166,000 milesRapid City, SDPower train

    The contact owns a 2020 GMC Sierra 2500. The contact stated that while driving approximately 70-80 MPH, the transmission downshifted, and the rear wheels locked up. The contact was able to coast to the side of the road. The contact was unsure if a warning light had illuminated. The vehicle was towed to the dealer, where it was diagnosed and determined that the transmission had failed and needed to be replaced. There were metal shavings found mixed in with the transmission fluid; however, the vehicle remained with the dealer unrepaired. The contact was informed by the dealer that the warranty had expired, and the vehicle could not be repaired. The manufacturer was notified of the failure but declined to assist in covering the cost of the repair. The failure mileage was approximately 166,000.

    NHTSA complaint 11679851
15. Filed Jul 7, 2025Failure Jun 28, 2025125,000 milesSalisbury, MAPower train

    The contact owns a 2020 GMC Sierra 2500. The contact stated that while her husband was driving 30 MPH, the rear wheels locked up and the vehicle skidded to a complete stop. No warning lights were illuminated. The vehicle was towed to the dealer, who diagnosed a failure with the transmission. The contact was informed that the transmission had imploded and needed to be replaced. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 24V797000 (Power Train); the VIN was included but the vehicle had not been repaired. The manufacturer was not notified of the failure. The failure mileage was 125,000.

    NHTSA complaint 11671648
16. Filed Jun 24, 2025Failure Jun 20, 2025Colorado Springs, COPower train

    What component or system failed or malfunctioned, and is it available for inspection upon request? - Transmission Valve Body resulting in a P0700 & P0747 code. Yes currently installed in vehicle. How was your safety or the safety of others put at risk? - When the vehicle goes into a limp mode to protect the transmission and rear-wheel lock up, the truck shuttered and hard downshifted. Speed limit is restricted to 5th gear only. I've been instructed by GM to continue driving and using the vehicle until the problem happens again, knowingly putting myself and others at risk on a second failure that could happen at any time. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes this is a common problem with a recall #N242454440, NHTSA 24V-797. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Mine has been rejected by GM. Although I documented and photographed the failure codes, I cleared them from the vehicle in order to attempt to safely get to the dealer and prevent further damages. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? At the time of failure yes, check engine light and codes from an engine monitor coinciding with the known problems. Engine speed / power was reduced to allow only 5th gear.

    NHTSA complaint 11668939
17. Filed May 17, 2025Failure May 12, 2025San Rafael, CAPower train

    After the transmission recall was completed, I’m now having erratic shifting. Having the recall adding software monitoring for a hardware issue is inadequate. Now that I am out of warrentee, gm has not resolved the issue and now I am having shifting problems.

    NHTSA complaint 11661620
18. Filed May 14, 2025Failure Apr 20, 2025Olympia, WAUnknown or other

    Cracks in the rear sliding window plastic upper rail glass guide causing Rear window leaking water and causing mold from water leaking. GMC has a service bulletin number 18-NA-383 knowing of this issue and not telling customers purchasing the GMC vehicle. The service bulletin was released in 2019 before purchasing the truck and they still didn't inform the customers. My child rides in the back in a car seat and now has been breathing in this mold and mildew for how long. I have had my vehicle in with Titus will Gmc in olympia multiple times for service and inspection of various recalls and still didn't inform me of this issue.

    NHTSA complaint 11660995
19. Filed May 13, 2025Failure May 9, 2025Alburtis, PAUnknown or other

    Tailgate unlatches unexpectedly. Has happened while parked and while driving. Almost caused accident to others.

    NHTSA complaint 11660582
20. Filed May 1, 2025Failure May 1, 2025Opelika, ALPower train

    The contact owns a 2020 GMC Sierra 2500. The contact received notification of NHTSA Campaign Number: 24V797000 (Power Train); however, the part to do the recall repair was not yet available. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was not made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.

    NHTSA complaint 11658105