2020 Chevrolet Silverado 3500 problems

UNKNOWN OR OTHER

Transmission will not shift into high gears throws engine code

NHTSA complaint #11758710 — an unverified report by a vehicle owner.

POWER TRAIN

VIN: [XXX] Make/Model/Year: 2020 Chevrolet Silverado 3500HD, Duramax L5P, Allison 10L1000 Recall: N242454440 / N242454441 (NHTSA 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)

NHTSA complaint #11757341 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11748501 — an unverified report by a vehicle owner.

FUEL/PROPULSION SYSTEM

The fuel pump driver module. I filled my truck up with diesel and it drove home fine. Later that afternoon left the house and got half mile down the road and the truck just shut off with no warning lamps or message. When this happened, you could not steer the truck and the brakes barley worked, now after the truck cut off a message came to shift in neutral. I was lucky no one was on the road at that time. Now had this happened the day before when I was coming home pulling a 40ft fifth wheel, this could have been catastrophic. When this fuel pump module goes out you have no warning the truck cuts off and you have no steering or brakes. This module needs to be recalled, and something else done to have some kind of warning before everything shuts off. People get these trucks to pull things and sooner than later Chevrolet will be answering to a fatality due to this fuel module, this does not need to be ignored till this happens.

NHTSA complaint #11747679 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11730919 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11724870 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11716298 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11714523 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11690678 — an unverified report by a vehicle owner.

VISIBILITY/WIPER

I am writing to formally submit a complaint regarding a recurring and unresolved mechanical defect in my 2020 Chevrolet Silverado 2500HD, which I believe may constitute a widespread safety and reliability concern affecting this vehicle model. Since I purchased the truck in June 2020, I have experienced seven (7) failures of the air conditioning compressor system. The first six failures were repaired at authorized Chevrolet service centers, and the vehicle is currently undergoing a seventh replacement. All repairs have been documented and performed through Chevrolet dealerships, and I am attaching copies of the service repair orders for your reference. On July 24, 2025, a Chevrolet Customer Assistance representative, Chana Padgett, confirmed to me that the A/C compressor has been on national backorder, which I was told was due to the frequency of failures reported in 2020 Silverado 2500HD models nationwide. This points to a systemic defect, not an isolated case. The vehicle now has approximately 54,000 miles, and the repeated failures have resulted in: Significant loss of use of the vehicle Extended downtime due to backordered parts Decreased resale value and overall reliability Excessive repair costs, inconvenience, and loss of productivity The continued failure of a critical component like the A/C compressor affects not only driver comfort, but also visibility and ventilation—especially in southern states during peak summer months—posing potential safety hazards. I urge the NHTSA to initiate an investigation into this matter to determine if a recall or further corrective action by General Motors is warranted for the 2020 Silverado 2500HD model line.

NHTSA complaint #11677321 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11672413 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11672413 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11671963 — an unverified report by a vehicle owner.

TIRES

Goodyear Wrangler Trail Runner AT LT275/65R20 126/123S I had been traveling at 55 mph when I started noticing a vibration in the steering wheel and front wheels. It started getting a little more noticeable, so I pulled over and checked out the front tires. I checked the lug nuts, looking for missing wheel balance weights, and checked the tires for any bulges. Everything seemed to be ok. Started driving again and the vibration was still there. As I was slowing down for a traffic light, the tire tread separated, and I pulled over. The tire remained inflated so I didn't hurt the rim. I changed the tire and after I get home the tire blew out.

NHTSA complaint #11670278 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM: INTEGRATED TRAILER BRAKE CONTROL

The contact owns a 2020 Chevrolet Silverado 3500. The contact stated that while hauling a 2020 Heartland Cyclone, the trailer brakes unexpectedly deactivated. The contact stated that the trailer brake was disconnected, and the warning light to check the trailer winch was illuminated. The vehicle was taken to the dealer, who was unable to determine the cause of failure. The vehicle was not repaired, and the failure persisted. The vehicle was returned to the dealer and the contact was informed that the trailer brake module had failed and needed to be replaced. The trailer brake module was replaced. The failure and repair were linked to an unstated Technical Service Bulletin; however, the VIN was not included. The TSB stated that the RV battery was interfering with the vehicle battery and causing the failure. The contact stated that the failure persisted. The vehicle was returned to the dealer but was not diagnosed or repaired. The manufacturer was informed of the failure. The manufacturer referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 52,000.

NHTSA complaint #11668128 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11657965 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11646659 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11641761 — an unverified report by a vehicle owner.

ENGINE

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 complaint #11641761 — an unverified report by a vehicle owner.

ENGINE AND ENGINE COOLING:ENGINE:CRANK/CAMSHAFT POSITION SENSOR

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 complaint #11641761 — an unverified report by a vehicle owner.

FUEL/PROPULSION SYSTEM

Received a code P10D9. Infotainment center says 157 miles until 65 mph max speed. Dealer has no idea what’s wrong

NHTSA complaint #11637246 — an unverified report by a vehicle owner.

SERVICE BRAKES

During operation of the vehicle at approximately 45mph and sudden stopping/ breaking is required, truck fails to do so. It is a partial loss of brake pressure and a loud "whale cry" type sound that appears to be coming from under the hood. I have had it happen twice just recently; I have taken to dealer, and they cannot replicate the issue. I have caught the sound the second time on video. To summarize truck loses partial breaking power, pedal does not bottom out, but it feels like there is not as much pressure being applied to the breaks when needed. Once the sound stops all braking returns to normal.

NHTSA complaint #11636906 — an unverified report by a vehicle owner.

LATCHES/LOCKS/LINKAGES

The contact owns a 2020 Chevrolet Silverado 3500. The contact stated that upon commencing to drive at various speeds, the tailgate would open without user intention, and remain open despite attempting to shut close via the interior controls. The local dealer was contacted and confirmed the VIN was not included in the NHTSA Campaign Number: 24V060000 (LATCHES/LOCKS/LINKAGES). The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 65,000.

NHTSA complaint #11634855 — an unverified report by a vehicle owner.

POWER TRAIN

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 complaint #11632943 — an unverified report by a vehicle owner.