2020 Chevrolet Silverado 3500 transmission problems

Filed Aug 17, 2026 · Transmission · AZ

VIN: [XXX] Make/Model/Year: 2020 Chevrolet Silverado 3500HD, Duramax L5P, Allison 10L1000 Recall: N242454440 / N242454441 (the federal safety agency 24V797) Description: Vehicle had N242454440 completed May 2026 (TCM software update for harsh shift / wheel lockup). On XXX at 103k miles, vehicle exhibited same defect: harsh downshift 8th-9th gear, CEL on. Diagnosed as TCM failure per N242454441. Vehicle at O'Reilly Chevrolet Tucson since XXX (18 days out of service as of XXX). Dealer states TCM on national backorder, SPAC ticket opened, no ETA. Dealer denied courtesy transportation stating out of warranty at 103k, despite recall being federal safety recall with 15yr/150k special coverage. This is failure of remedy for safety recall that can cause momentary rear wheel lockup. No parts available, no transportation provided. What I want: GM to provide rental coverage and expedite TCM repair per recall obligations. Owner: [XXX], [XXX], [XXX], [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jul 6, 2026 · Transmission · VA

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.

Filed Apr 13, 2026 · Transmission · WI

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 (the federal safety agency 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.

Filed Mar 17, 2026 · Transmission · TN

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)

Filed Feb 6, 2026 · Transmission · TN

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.

Filed Jan 30, 2026 · Transmission · IA

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.

Filed Sep 30, 2025 · Transmission · UT

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 the federal safety agency 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. the federal safety agency 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)

Filed Jul 10, 2025 · Engine, Transmission · 28,000 miles · FL

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 the federal safety agency 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.

Filed Jul 8, 2025 · Transmission · KY

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 the federal safety agency 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.

Filed Apr 30, 2025 · Transmission · CO

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.