2020 Chevrolet Silverado 3500 Powertrain (other) Problems

Since buying the vehicle I’ve had issues with the truck going into limp mode with codes p0700 as well as p0747. I have taken it to the dealership twice now, when it has arrived the codes were no longer there. Every time the truck went into limp mode the transmission would get stuck into 5th gear stuck at 45 mph. The problem with the truck started at 48,000 miles, the truck currently has 60,000 miles and the problem has been more active. With the dealership not wanting to resolve the issue the truck was taken to another shop to try to fix the transmission.

NHTSA ID

11748501

Incident

Sep 1, 2025

The transmission, without warning, intermittently locks the rear wheels when towing a 13,500 lb 5th wheel RV. It occurs when going uphill and the transmission downshifts to maintain torque. The "D" on the gear indicator on the dashboard also flashes 3-5 times. This is a known issue with the Allison approved (but GM made) transmission from model year 2020 to 2022 (NHTSA 24V-797) and is to be under extended warranty. We brought it to a Chevy dealer who kept from March 24 to April 9, without any resolution as they could not replicate the error which only happens under load travelling uphill. I also openedd a case with Chevrtolet Customer Service, who apparently does not have any ability to compel GM corporate techs or dealerships to fix the issue described without an error code. Historically, the truck throws error codes routinely and we have spent several thousand dollars trouble shooting the communication issues, also without resolution. We live in Wisconsin and were on vacation near Los Angeles, CA and had to transport it back home, leaving our RV in storage in California. At present, the only path to repairing the truck is to pay for the transmission repair ourselves. GM still does not have a long term solution for the tranmissions they now manufacture.

NHTSA ID

11730919

Incident

Mar 24, 2026

This is a supplemental update to complaint #XXX filed February 7, 2026, regarding my 2020 Chevrolet Silverado 3500HD Diesel (VIN: [XXX] ). The vehicle experienced a sudden and complete loss of propulsion on January 21, 2026, consistent with the defect mechanism described in Recall 24V797. Recall software was installed May 27, 2025. Failure occurred eight months later with no warning. GM's response has been as follows: A Field Technical Service Engineer made a remote determination that the failure did not match the recall without physically inspecting the transmission. GM Executive Resolution required teardown at customer expense with no reimbursement guarantee. The authorized dealership (Dave Kirk Chevrolet, Crossville TN) declined to perform a documented inspection -- citing unwillingness, not inability. Written refusal was withheld for over one week. GM's Executive Resolution liaison admitted she had known of the refusal and withheld that information from me, directly delaying my ability to act. The final repair order (RO 50479) contains a self-documented notation: "Added tech notes 3/16/26" -- eight weeks after the January inspection. The transmission pan was fully removed, fluid was discarded, and pan bolts were not reinstalled. The only photograph provided does not reflect as-found conditions. Evidence integrity has been materially compromised. The vehicle has been without propulsion since January 21, 2026. Full chronology, documentation, and supporting evidence are attached. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11724870

Incident

Jan 21, 2026

The vehicle experienced a sudden loss of propulsion while driving at highway speed after normal operation. The transmission began slipping and then would no longer engage gears. The vehicle had to be pulled over and towed. This vehicle is subject to GM Recall N242454440 related to a known transmission control valve defect that can cause loss of propulsion. I was not notified of this recall by GM and discovered it independently. Once aware, I completed the recall software update. After the failure, the dealer documented pressure control fault codes (P0746 and P0798), burnt transmission fluid, and internal debris, and recommended full transmission replacement. I requested that GM evaluate whether this failure is related to the known defect addressed by the recall and Special Coverage N242454441. GM acknowledged my escalation request but did not schedule an inspection, did not contact the dealer, and closed the case without performing a causation review. The vehicle remains disabled, no technical inspection has occurred, and I am incurring rental costs. I am reporting this as a safety-related failure and recall handling concern.

NHTSA ID

11716298

Incident

Jan 21, 2026

While driving at highway speed in my 2020 Chevrolet Silverado 3500 Duramax, the transmission suddenly failed and locked up without warning. This caused an immediate loss of vehicle function and created a dangerous situation while traveling in traffic. I had my two children in the vehicle at the time. I was able to safely maneuver the truck to the shoulder, but the vehicle was no longer operable and required towing. This failure occurred only a few months after a transmission replacement and follows prior transmission repairs, including a valve body replacement performed by a GM dealership. This is a repeat transmission failure and presented a serious safety risk due to the sudden nature of the failure at highway speed.

NHTSA ID

11714523

Incident

Jan 30, 2026

On [XXX], while driving ~65 mph, my 2020 Chevrolet Silverado 2500HD Duramax experienced a sudden transmission lock-up, nearly causing a crash. The event caused severe internal transmission damage, leaving the truck unsafe and inoperable. This is the exact defect described in NHTSA Recall #24V-797 (GM Recall N242454440), which states that valve body wear can cause rear-wheel lock-up. My truck stored P0700 and P2820, which directly indicate a valve body failure. GM refuses to repair my vehicle under Special Coverage N242454441 (15 years/150,000 miles) because code P0747 did not set, even though my failure clearly matches the defect. I requested a hydraulic valve body leak test, the only way to confirm the defect, but the dealer refused, saying they only scan codes. GM must perform this test at no cost, as required by federal recall laws. GM’s denial leaves a known safety defect unrepaired, violating federal recall obligations and putting drivers at risk. NHTSA action is needed to require GM to repair vehicles like mine, regardless of which DTC is stored. VIN: XXX Mileage at failure: 145,560 Dealer: Ken Garff Chevrolet – American Fork, Utah GM Case #: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11690678

Incident

Sep 17, 2025

The contact owns a 2020 Chevrolet Silverado 3500. The contact stated that the check engine warning light was illuminated. Additionally, the vehicle later failed to start and became undrivable. The dealer was notified of the failure and an appointment was scheduled for diagnostic testing and for the manufacturer internal recall repairs. The vehicle was not diagnosed or repaired. Additionally, the contact became aware that the VIN was included in NHTSA Campaign Number: 24V797000 (Power Train); however, the local dealer was contacted and informed the contact that the dealer was not aware of the recall. 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 via email, but no assistance was provided. The failure mileage was approximately 28,000. Parts distribution disconnect.

NHTSA ID

11672413

Incident

Apr 10, 2025

Mileage

28,000 mi

The contact owns a 2020 Chevrolet Silverado 3500. The contact stated while driving 65 MPH, the rear wheels locked-up. The contact was able to pull over to the side of the road. The contact resumed driving, but the vehicle was driving roughly, and the failure recurred while driving 30 MPH. The check engine warning light, the electronic stability control warning light, and other unknown warning lights were illuminated intermittently. The contact pulled into a gas station, where a mechanic inspected the vehicle, but the cause of the failure could not be determined. The vehicle was towed to the dealer, where it was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired due to the cost. The contact related the failure to NHTSA Campaign Number: 24V797000 (Power Train); however, the VIN was not included in the recall. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was unknown.

NHTSA ID

11671963

Incident

Jun 4, 2025

I recieved a recall notice from Chevrolet stating they needed to install a software update to the truck which will warn if a potential rear wheel lock up is about to occur due to faulty transmission valve body- which was stated that they do not have a fix for. After software update was installed- I was driving about 35 mile per hour on the trip home, and the truck abruptly downshifted very hard, momentarily locking up rear wheels, and the check engine light came on, and the vehicle message came up stating the vehicle was placed in a reduced propulsion mode(limp mode). The next day it did it again on my short drive to work of 2 miles. I took into dealership and they informed me that the valve body had failed- as mentioned in the recall notice. It is now 1 month later and I still do not have my truck back, the part is back ordered, and they have no idea when it will be fixed. I am without my primary form of transportation.

NHTSA ID

11657965

Incident

Mar 25, 2025

The sudden rear wheel lock up recall that GM has released for the 2020+ Silverado's with the 10-speed transmission does not go far enough. The recall simply reprograms the PCM to alert the driver 10,000 miles prior to the valve in the valve body failing, puts the vehicle into limp mode, and extended the warranty on the valve body to 15 years or 150,000 miles. GM states there is no fix available and this is not correct. NextGen Drivetrain has developed a fix for this per their website [XXX] ). On their site they also provide videos of trucks experiencing the lock up where it seems that the vehicle downshifts to 2-nd gear at high speeds and creates a violent jolt. This is extremely troubling to me as these vehicles are meant to tow, and I am very fearful that this issue will happen while towing a long trailer while my family and I are traveling and putting them in danger of an accident. It is very concerning to me that NHTSA would allow for this type of a "FIX". I am not sure if you have seen the videos of this issue happening, or know that a fix does seem to have been developed. I ask that you please reopen this investigation and revisit the way GM is handling this recall, and look into the fix that NextGen drivetrain has developed. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11646659

Incident

Mar 6, 2025

The contact owns a 2020 Chevrolet Silverado 3500. The contact stated that while driving on [XXX] at 70-73 MPH, the vehicle unexpectedly downshifted to first gear. The contact slammed on the brake pedal and pulled over to the side of the road. The vehicle was turned off. The contact stated that the tachometer had increased to over 3,000 RPM. The vehicle then red-lined. There were no warning lights illuminated. The vehicle was taken to the local dealer, where it was diagnosed that the valve body control needed to be replaced but was on backorder for a month. The vehicle was repaired, but the vehicle failed to recognize the part. The dealer informed the contact that the transmission needed to be replaced. The vehicle was repaired, but the failure recurred. While driving, there was an abnormal knocking sound coming from the vehicle. The contact was able to pull over safely. The vehicle was towed to another local dealer, Spitzer Chevrolet Amherst (200 N Leavitt Rd, Amherst, OH 44001), where it was diagnosed and determined that the engine needed to be replaced. The contact was informed that the torque converter was wobbling, and the crankshaft bearings were shot. The vehicle was not repaired. The vehicle was towed to an independent mechanic who determined that the oil filter had metal shavings inside. They removed the oil pan and noticed the crankshaft had broken in half. The vehicle was not repaired. 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 178,000. Parts distribution disconnect. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11641761

Incident

Dec 1, 2024

Mileage

178,000 mi

The contact owns a 2020 Chevrolet Silverado 3500. The contact received a notification of NHTSA Campaign Number: 24V797000 (Power Train) however, the part to do the recall repair was not yet available. The contact stated that while driving at 62 MPH during snow weather and switching lanes; the accelerator pedal was depressed, and both the rear wheels had locked. The vehicle spun out of control and traveled into the center lane of a two-lane road and crashed into a snow embankment where it came to a stop. No Injuries were sustained. No warning light illuminated. Prior to the crash, the contact stated that the transmission was slipping and making abnormal noises where it was taken to a dealer for the transmission was inspected and replaced due to metal shaving intrusion. The vehicle was then taken to the same local dealer for the most recent failure where it was diagnosed with a transmission failure related to the open recall. The vehicle was towed back to the residence where it was informed that the recall remedy was not available and no interim repair. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The failure mileage was approximately 40,000. The contact mentioned that the failure mileage for the most recent failure was 28,000 with the new transmission. The manufacturer was made aware of the failure and confirmed that there was no recall remedy available and no expected available date determined. VIN tool confirms parts not available.

NHTSA ID

11636312

Incident

Dec 30, 2024

Mileage

40,000 mi

Dealership told me the throttle body failed in my transmission. I wanted it completely torn down to find the actual point of failure since it did represent the current recall on the truck that hadn't been done because the part isn't yet available. The transmission has been replaced for almost $10,000.00

NHTSA ID

11632943

Incident

Oct 28, 2024

2nd time I’ve had to replace def heater and tank. Truck goes into limp mode and limits the speed leaving a person stranded.

NHTSA ID

11630257

Incident

Dec 11, 2024

Transmission lock up traveling 45 miles an hour while acceleration up modest uphill grade pulling a 3000 pound trailer. The lockup was severe enough to cause passengers to lunge forward with seatbelt engagement. There was no loss of control of the vehicle; however, we did stop the vehicle to inspect it with no damage observed. We expected to see some. This event would have caused a likely loss of control of the vehicle if the lockup was for longer duration. Vehicle also had prior hard shifts that are still occurring. These hard shifts usually occur in the lower gears with acceleration and deceleration. Vehicle was taken to the dealership with an explanation of the event. There were no codes. The dealer recommended a transmission fluid change to smooth the shifting. This seemed to decrease the frequency of the hard shifts but did not eliminate them. The vehicle has not been inspected by police, manufacture or insurance company. The dealer did not do a thorough transmission inspection. I suspect they knew of this problem at the time of the transmission fluid change due to the current recall: Manufacturer Recall NumberN242454440 NHTSA Recall Number24V797

NHTSA ID

11624953

Incident

Sep 11, 2024