Power Train Problems of GMC Sierra 2500 - part 2

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.

See all problems of the 2020 GMC Sierra 2500 🔎.

Problem #1: trailer brakes failed while pulling 40' fifth wheel trailer. Was driving at about 50mph on a 55mph road and was approaching a stop light. I went to apply my truck and trailer brakes simultaneously and quickly found out I had "lost" my trailer brake. This happened another two times within the next 10 mile trip to my house. I immediately disconnected my trailer and took my truck to the shop. The GMC dealer fixed this issue, however, it is both scary and extremely dangerous to the public when something like this happens on a brand new truck. Problem #2: right around 30,000 miles I was driving (unloaded) down the road at about 35mph when I felt a hard clunk in the transmission followed by grinding noises - immediately a notice flashed on the dash stating the truck went into reduced acceleration and the check engine light came on. I brought my truck to a local GMC dealer to be serviced on June 19th and they advised me it was the allison transmission valve body. The part has been on back-order and my truck is still at the dealership sitting in the back lot with at least 4 other 2024 hd models. I called gm twice to inquire about safety recall n242454440 (covering 2020-2022 gm vehicles) and recommend that it get extended beyond 2022 since the problem with the transmission valve body has not been resolved yet. I have not heard anything back from them since that call back in June.

See all problems of the 2024 GMC Sierra 2500 🔎.

The contact owns a 2023 GMC Sierra 2500. The contact stated while driving 35 mph, the vehicle gear shift was shifting independently, and the contact noticed the vehicle was shaking and the vehicle went into limp mode. The check engine lights illuminated. The contact pulled over to the right side of the road turned the vehicle off and then turned the vehicle back on and the failure persisted. The contact the gear shift was stuck in fifth gear. A dealer was contacted. The vehicle was taken to the dealer where it was diagnosed that the valve body needed to be replaced. The vehicle was not repaired. The manufacturer was notified on the failure and opened a case. The contact was referred by the manufacture to report the failure the approximate failure mileage was 50,823.

See all problems of the 2023 GMC Sierra 2500 🔎.

I rely heavily on this vehicle for my business and within 1 year of ownership, the vehicle broke down on the highway allowing it to only run @ 30mph. After finally locating a dealer who could evaluate the vehicle in less than 1 week, I was informed that the part was unavailable and they indicated, "it could take 1 month or 3 months to receive. " following multiple conversations, I was forced to open a claim with gm customer care. While trying to get information, I was, at one point, told that "although the code indicates failed transmission control module, it doesn't happen all the time and if I wanted to drive it I could come and take it until the part arrives. " that really told me alot about how gm representatives view safety while when it happened, I was on interstate and nearly got trounced by oncoming heavy traffic while pulling an equipment trailer. After the case was handed off to several gm customer care representatives, I finally rec'd feedback including several email updates. I finally rec'd the vehicle back after 1 month and was informed that 1) would receive car payment from gm & 2) would receive additional compensation for lost work time while my vehicle was out of service (Jan 2024). Since that conversation, I did receive 1 car payment however, never heard back from alisa regarding "lost time". I have sent several emails to customer care asking for an update however, crickets. Furthermore, the car has returned to the shop for another warning to "shift vehicle to park" when it was in park. They told me its a electrical malfunction but they could not get the error to come up on test. I have a photo showing the error.

2024 GMC denali hd with approx. 12, 500 miles: the truck is constantly going into limp mode. Driving down the road, first it feels like the wheels lock up with a loud noise. Immediately goes into limp mode and check engine light comes on. Took it to the dealer yesterday 6/3/25 for repairs. I just spoke to my service advisor this morning where I was told it was the valve body of the transmission that needed to be replaced. However, they were on backorder and have no eta on when they will get a replacement.

I was driving home from work and my truck down shifted and rear wheels locked up, now it’s in limp in mode and will not shift.

See all problems of the 2022 GMC Sierra 2500 🔎.

Vehicle transmission locked up and brought me down to 20-30mph out of the blue at [xxx] . Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Two times with my truck, the transmission has locked up solid while towing a heavy load almost causing my load to shift and wreck my truck in traffic. It happened at 60k miles and again at 68k miles. The truck shutters and then locks up solid on the transmission, then after a second of sliding, it releases and goes into limp mode. This is a serious issue when it is uncontrollable. It felt like my trailer had broken loose and slammed into the cab when it happened. I'm sure it wasn't good on the truck in general. A code scanner read p0747 code and it appears that Gmcs recall does not cover my truck in another recall for the same issue with 20-22 model trucks. It is happening all the way up to the 25 year models from what I read.

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.

Transmission fluid overheating, which is a known issue in other gm models with 6. 6l diesel with 12 speed allison transmission. Confirmed by warning message received on dashboard and transmission fluid temperature gauge. This occurred within 3 weeks of purchase. Dealer confirmed “valve” needs to be replaced. Part is on back order with no arrival eta. Service advisor indicates the truck is not safe to drive and remains in the service department.

See all problems of the 2025 GMC Sierra 2500 🔎.

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.

This issue is pertaining to the valve body in my 10-speed transmission. While I was traveling home, the truck experienced a “wheel lockup”. The transmission shifted down aggressively, then putting the truck into limp mode. I had to travel the rest of the way home with a max speed of 35 mph. I have been without this truck for 3 months waiting on parts. This is absolutely unacceptable from gm. Extremely unsave.

Shift to park message displayed while attempting to shut off engine after shifter was in the park position, accessory would not turn off even after driver door opened and could not leave vehicle.

The contact owns a 2020 GMC Sierra 2500. The contact stated that the vehicle was under NHTSA campaign number: 24v797000 (power train) and the vehicle was repaired. The contact stated that after the recall repair the transmission started shifting hard. The vehicle was taken to the dealer and the contact was informed that the transmission module would reprogram independently and adjust independently. The contact stated that a a week later while driving approximately 45 mph, the vehicle started to run rough, and the message engine power reduced was displayed. The transmission fault, parking brake system alert, service parking brake, and the check engine warning light illuminated. The vehicle was towed to the dealer who diagnosed the vehicle and determined that the fuel injector was open, causing high resistance in the connector for cylinder #4. The transmission could not be diagnosed until the injector was repaired. The manufacturer was informed of the failure and opened a case. The failure mileage was 125,000.

The contact owns a 2023 GMC Sierra 2500. The contact stated while driving approximately 40 mph, the vehicle shook abnormally twice and then switched to low power mode. The contact stated there was no warning light illuminated. The contact had the vehicle towed to a local dealer, where it was diagnosed and determined that the transmission valve body needed to be replaced. The contact stated that the valve body had failed within one and a half year. The contact requested that the entire transmission be replaced. The manufacturer was informed of the failure and declined to replace the transmission. The vehicle was not repaired. The failure mileage was approximately 42,000.

Radiator hose connection broke and loose fluid and transmission got broken.

See all problems of the 2021 GMC Sierra 2500 🔎.

2023 GMC Sierra 2500 at4 with approximately 36,000 miles as of current. The vehicle has experienced three valve body failures to date. GMC dealerships have completed one gm remanufactured transmission replacement and an overhaul of the second transmission. The third valve body has now failed. A GMC transmission specialist confirmed transmission failure upon recent test drive on 2/24/2025. GMC dealership refuses to perform warranty repair as they are stating “a recall is being developed” therefore will not repair/replace current defective powertrain parts. I was given the vehicle back with the verbal disclaimer “it should be safe to drive but the rear wheels can lock up at highway speed so be aware. ” the failure causes extreme harsh downshifting and what feels like a momentary rear wheel lock up. I have experienced this numerous times at lower speeds (<40mph). The check engine light does not come on.

Odi # 11646185 my truck on [xxx] leaked transmission coolant from the jumper line leak( which this part is recalled but not for my VIN #) $400. 61 dollars and left me stranded in the middle of the highway and had to be towed. After the repair and checking the transmission was discovered it was ruined because of the leak. So now I have to have a new transmission installed at jennings in beardstown IL to the cost of $7363. 39. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

The contact owns a 2020 GMC Sierra 2500. The contact stated while driving 30 mph, the engine revved while the vehicle lost motive power in the middle of the road. The contact was unable to pull over to the side of the road. The vehicle was restarted but was undrivable. An unknown warning light was illuminated. The contact stated that while the vehicle was being towed, there was a significant amount of fluid leaking onto the ground. The vehicle was towed to ryan's repair, where it was diagnosed with a fractured transmission cooler line. The vehicle was not repaired. The mechanic related the failure to an unknown recall. The dealer was not notified of the failure. The manufacturer was notified of the failure, but no assistance was provided because the VIN was not included in the TSB. The failure mileage was approximately 112,000.

Hard shifting. Back wheels locking up.

Transmission not shifting correctly. Have had the recall software update. Two new valve bodies and still not shifting correctly. Transmission is known to lock up.

My truck had been sitting idling for about 20 minutes on a job site on flat level ground. I turn around for whatever reason and my truck is driving forward with on one in it but my dog. The truck ran into an out rigger on my crane. I had 3 of my employees there that witnessed this happen. I got into my truck and the shifter was in drive. Somehow my dog was able to shift my truck into drive from park while it was sitting idle. I have 3 eye witnesses as well as pictures of the incident. I have pictures but was no able to upload them to they portal.

The contact owns a 2024 GMC Sierra 2500. The contact stated that transmission fluid was leaking onto the garage floor. The contact stated that while driving at an undisclosed speed, the transmission hesitated before shifting. The contact stated that the check transmission warning light was illuminated. The vehicle was taken to a local dealer; however, the dealer was unable to diagnose the vehicle. The vehicle was not repaired. The contact had inquired if the transmission needed to be replaced, and was informed that transmissions were on a national back order. The manufacturer was not informed of the failure. The failure mileage was 8,808.

The contact owns a 2020 GMC Sierra 2500. The contact stated while driving at an undisclosed speed, the accelerator pedal was depressed, and the transmission jerked. The contact stated that the transmission was skipping gear while shifting. The check engine warning light turned on and off. 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 made aware of the issue. The failure mileage was approximately 114,000. VIN tool confirms parts not available.

I leased this vehicle on may 17, 2024, expecting it to function as intended. Instead, within months, it suffered recurring and escalating failures that have rendered it unsafe and unusable. January 7, 2025, I brought the truck to gates GMC for routine service and reported that it had lunged forward by approximately 2 to 2. 5 feet while shifting into park. Additionally, it exhibited irregular acceleration and rough down shifting in lower gears. I also communicated the check engine light has come on and gone off on the dashboard over the past week a few times without receiving any information on the app. At this January 7th visit, gm performed recall n242435631, supposedly addressing a known battery drain defect that caused total vehicle shutdowns. On January 24, 2025, I started the truck and was immediately overwhelmed by an intense chemical odor coming through the ventilation system. January 31 – February 1, 2025 – erratic engine warning lights & diagnostic failures on January 31, 2025, at 5:28 pm, on this key cycle the check engine light illuminated but failed to register in the gm app. On the next key cycle, the warning disappeared. The following morning, February 1, 2025, at 10:26 am, the check engine light appeared on the first key cycle before disappearing on the second key cycle. The onboard diagnostics system failed to log or retain these warnings. On February 7, 2025, the vehicle suffered a complete electrical failure. No electronic function whatsoever. Roadside assistance attempted to jump-start the truck using a high-powered jump pack, but it remained inoperable. A Ford super duty and jump pack were needed to force start the truck. February 10, 2025 the truck suffered another total electrical failure and required towing to gates GMC. The app indicated the brake system, anti-lock braking system, emissions system (specifically the exhaust system), and power train requiring service. My truck is at gates GMC and was drawing 90 milliamps opposed to 40.

The contact owns a 2020 GMC Sierra 2500. The contact stated while driving 63 mph, and towing a 15,000 lb. 5th wheel RV, the contact heard the rear wheels make an abnormal squealing or chirping sound. The contact stated that the front end of the vehicle was pulling to the right. The contact adjusted the steering wheel to the left to compensate. The contact stated that the vehicle was losing motive power. The contact stated that the drive(d) symbol was flashing on the instrument cluster. The contact depressed the accelerator pedal; however, the vehicle failed to respond as intended. The contact exited the highway and stopped the vehicle. The contact had the vehicle towed to an independent mechanic. The mechanic scanned the vehicle but had not retrieved any fault codes. The mechanic researched online and informed the contact that the VIN was included in NHTSA campaign number: 24v797000 (power train) for a defective transmission control valve. The contact was referred to a dealer by the mechanic. The vehicle was not repaired. The contact had the vehicle towed to a local dealer who diagnosed the vehicle and determined that the transmission needed to be replaced. The contact was informed that the transmission was not covered for repairs if damaged while performing the recall repair. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 112,000.

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 manufacture was made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.

The vehicle will be in the park position and a warning on the dash will say shift to park not allowing you to shut off the vehicle. Jiggling the shifter sometimes works but often have to restart the vehicle numerous times to get the error message to not appear and be able to proceed with shutting off the vehicle.

The contact owns a 2020 GMC Sierra 2500. The contact received notification of NHTSA campaign number: 24v797000 (power train). After reading the context of the recall, the contact stated that the proposed remedy of a software update was not an adequate repair for the rear wheel lock up failure. The contact stated that the safety of the vehicle could not be trusted and believed that the vehicle was unsafe to operate. The local dealer was made aware of the issue and confirmed the recall remedy. The contact was referred to the manufacturer for further assistance. The manufacturer was made aware of the issue and the contact proposed a buyback offer for the vehicle which the manufacturer denied. The contact was provided a case number. The contact had not experienced a failure. Parts distribution disconnect.

The contact owns a 2021 GMC Sierra 2500. The contact stated while driving 40-55 mph, the vehicle started losing motive power. The contact stated while pulling into a nearby independent mechanic shop, the vehicle started jerking significantly and stalled midway. The check engine warning light was illuminated. The mechanic diagnosed the vehicle with transmission failure. The vehicle was towed to the residence. The local dealer and several unknown dealers were notified of the failure and informed the contact that the transmission assembly was not available and could not be ordered. The vehicle was towed to cj's transmission, where the transmission was taken apart. The mechanic determined that the transmission needed to be replaced. The vehicle was being repaired with a rebuilt transmission. 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 made aware of the failure and offered a modest monetary compensation for the repair. The failure mileage was approximately 134,000. Parts distribution disconnect.

Experienced loss of power and inability to maintain highway speeds. The transmission shifted violently and rpms went as high as 3500. Was able to move off the highway but cars behind us had to Dodge us when it failed. There was warning message on the dash and a cel. The truck threw two codes p0700, p0747. I was able to limp to a dealer 5 miles away. This is a known TSB with gm. There is a solenoid failure in the transmission. There is 30-90 day backorder on parts as the failure is so prevalent.

2024 GMC sierra denali ultimate 3500hd equipped with duramax lp5 and allison 10 speed transmission mission. Towing cargo trailer Thursday November 21 up 4 degree incline transmission let loose banged and popped slammed to a stop almost causing accident and went to limp mode. Took to dealership in show low arizona. Was told this is common problem and it’s the valve body assembly and parts are 60-90 days out. Mind you this truck was ordered from factory and received in March of 2024. The truck has 21k miles. So now a vehicle I bought specifically for business to haul a spray trailer will be down 2-3 months with no loaner to use to operate our business.

The contact owns a 2020 GMC Sierra 2500. The contact stated while driving approximately 65 mph, the vehicle lost motive power. The contact stated that he had not depressed the brake pedal. The contact was towing a 20-foot flatbed trailer with a load of lumber approximately 4,000 lbs. In weight. The contact stated there was no warning light illuminated. The contact pulled over with the vehicle still running and attempted to shift into drive(d) and reverse(r); however, the vehicle failed to respond. The contact stated that after shifting into drive(d), several unknown warning lights illuminated. The contact had the vehicle towed to a local dealer; however, the vehicle was not diagnosed or repaired. The contact researched online and related the failure to NHTSA campaign number: 24v797000 (power train). The manufacturer was informed of the failure. The failure mileage was approximately 100,000.

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 made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.

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 made aware of the issue. The contact had not experienced a failure. VIN tool confirms parts not available.