GMC Sierra 3500 Problems — All Years, Common Issues & Reliability

I have had an incident where my 2023 gmc 3500 hd was had left me stranded earler this week. i towed the new truck to a certified dealer and i haven't heard anything since then. they mentioned my transmission will need to be fully replaced because valve body issues of solenoid a,e,f, are stuck open and closed codes on the 10 speed transmission upon researching my trucks history it was manufactured in 2022 and pulled out for sale october 2022 and i have seen. 242454441 special recall the same issues i experienced shudder and engine power reduced and no parking gear or driving. i need help and didnt have any warning of anything about this till now since it was showing my vehicle only had a tailgate issue which gmc didnt help me out when i had to pay for my taillight after firewood flew out with the tailgate opening in jan 2023 they said it wasnt a known issue then fixed the tailgate but not the taillight so i need help proving my truck belongs with the 242454441 class of recalls because not only does the transmission the exact same as previous models obviously 1000s of others are getting this issue thank you

The control arm bearing appears to have failed without warning causing loss of steering control. This occurred at low speed on a street in [XXX] last night near a gas station, so the driver was able to drive to a safe location easily without risk to life. Had the failure happened at speed a possibly fatal collision would have been likely. The vehicle has been used for the past 8 months to drive to work and has not been subject to any stress. It has not been modified. The tow truck driver said he has seen a number of other control arm failures recently, not necessarily in the same vehicle type. It may be due to bad pot holes this year in [XXX] , they are bigger and deeper than normal. This information is based on assessment by tow truck driver last night. Vehicle is at Jim Shorkey in Murrysville for repairs INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

While traveling at highway speed, the hood-mounted air vent (factory-installed component) on my 2022 GMC Sierra 3500 HD suddenly detached from the vehicle without warning. Upon separation, the vent was propelled backward, striking both the hood and the windshield. The incident occurred during normal driving conditions, with no prior indication of looseness, damage, or defect in the component. The force of the detachment caused damage to the hood and posed a significant safety risk, as the debris impacted the driver’s line of sight and could have resulted in loss of control or injury. There were no external factors (such as collision or road debris) that contributed to the failure. This appears to be a failure of the factory-installed component and its mounting system. Safety Concern: This type of failure presents a serious hazard not only to the vehicle occupants but also to other motorists. A detached component at highway speed could strike nearby vehicles, cause sudden driver distraction, or lead to more severe accidents.

The service department has identified "gasoline contamination" as the cause of a fuel system failure; however, this diagnosis is directly contradicted by both the shop’s internal test results and independent laboratory analysis.the shop performed an API Gravity test and a Styrofoam cup test.•API Gravity Result (35): According to GM Service Information (GMSi), the standard API range for #2 diesel is 30–39. result of 35 is a textbook "pass" for clean diesel. Gasoline contamination would typically spike this number into the 50s.GMSi protocol indicates that gasoline-contaminated diesel will melt a cup within 30 minutes.results only provided a "softened bottom," which is an inconclusive result per GMSi standards.Sinclair Refinery lab confirms the fuel sample taken from my vehicle is within 100% of factory specifications for diesel, with zero gasoline or DEF detected.Violation of GM Service Protocols even assuming the shop’s diagnosis of contamination was correct, the repair performed deviates dangerously from GMSi requirementsFor a 2024 L5P Duramax that has been cranked with contaminated fuel, GMSi (e.g., Bulletin 16-NA-376) mandates the replacement of the entire high-pressure fuel system, including the pump, both fuel rails, and all eight fuel injectors. shop replaced only the pump and cleaned the lines. This "partial repair" is not a GM-approved recovery procedure for contamination. Reusing potentially contaminated injectors and rails is the primary cause of catastrophic repeat failures.This clearly falls under warranty work and I should not had been charged for this repair. The dealership refusing to acknowledge my concerns and evidence is not only dangerous to the safety of myself and passengers, but raises concern for my vehicles future maintenance status, both inside and out of warranty. This shows a deceptive business practice and complete lack of accountability, compassion and moral understanding for the customer.I am owed a full refund and a warranty claim open

The contact owns a 2024 GMC Sierra 3500HD. The contact stated that while driving at various speeds, there would be a diesel odor coming into the cabin of the vehicle. The failure had become more persistent, causing black smoke to enter the cabin of the vehicle. The failure caused the contact and other vehicle passengers to have headaches, nausea, and dizziness. While driving approximately 65 MPH, the contact began speaking to their daughter, sitting in the front passenger seat, and noticed her not responding. When looking over, the contact noticed her daughter's head was lowered. The contact immediately pulled over to the side of the road, where she pulled her daughter out of the vehicle and called an ambulance. A fire truck was also dispatched in order to drive the vehicle to the fire department, where they tested the vehicle; however, they were unable to duplicate the failure. The contact's daughter was taken to the hospital, where it was determined that she had suffered from carbon dioxide poisoning. The vehicle was taken to the dealer, who diagnosed that the Diesel Particulate Filter (DPF) was clogged, and that the Exhaust Manifold and Turbo Inlet were both fractured, causing a blockage in the Engine Bank. It was determined that all the avenues through which air and carbon should have been exiting the vehicle had failed and were causing everything to come into the cabin of the vehicle instead. The vehicle was scheduled for repair; however, only the exhaust manifold could be repaired, while the other parts, such as the DPF and hose, were on national backorder and awaiting retrieval. The manufacturer was informed of the failure, and a case was opened. The contact stated the manufacturer had been avoiding acknowledging that black smoke had been entering the vehicle's cabin and had yet to resolve that issue. The failure mileage was approximately 20,000.

August of 2025 [XXX] purchased a certified GMC Sierra 3500. The truck had been traded in May and sat in their service department waiting on a valve body. At this point, we knew this. [XXX] had done research on it, and felt confident in being told the valve body was completely replaced and now working…. Worst mistake we’ve made in a long time. It was not replaced, that was only the beginning of the lies. [XXX] then drove the truck across the country for work, not knowing how much of a hazzard it was. Shortly after arriving there he quickly realized the truck was still having transmission problems. We brushed it off, these things happen. Fast forward when he came home in September/October he took the truck to the Rice Buick GMC service department. Where he was supposed to “wait” on his appointment. Only to call me hours later, they clearly weren’t going to be done that day. We left not knowing that it would be nearly a month until we could drive the truck again. In the midst of that they never offered any help, a rental or anything. When I asked, they offered a tiny small car next door at enterprise. I clearly did not agree, we just spent a lot of money on a heavy duty truck for a reason. It took multiple phone calls to multiple supervisors for them to agree to let him rent a truck. Because you know they might have to spend an extra penny or something (que the eye roll). In that month of having the truck the communication was little to non existent. They never answered the phone, called back, heck most of the time the text messages weren’t even replied to. It once again took me getting a little bit ridiculous for an answer - the truck was “fixed”. When I picked up the truck I spoke to the the service manager, and he of course tried to play me like I was some dumb women who had no idea what I was talking about. He dismissed all of my concerns, acted like having a truck for a month was normal. (More attached in photos) INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

This 2024 GMC Sierra Heavy Duty has experienced a continuous pattern of major mechanical and electrical failures since early ownership. The vehicle required a complete engine replacement under warranty at approximately 43,626 miles. Since that time, the vehicle has continued to experience repeated injector failures, control module faults, communication errors, and voltage-related system issues. Current diagnostic codes indicate multiple simultaneous failures including ignition relay feedback circuits, control module power faults, gateway communication loss, brake system communication faults, and battery voltage circuit errors. The dealership has diagnosed a power distribution / fuse block failure at approximately 79,000 miles. These electrical failures affect multiple vehicle systems and raise concerns regarding reliability and potential safety risks due to loss of communication between control modules and possible braking system interaction. The vehicle has been in the dealership numerous times for repairs including engine replacement, injector replacement, control module reprogramming, and electrical diagnostics. I am submitting this complaint due to concern over a potential systemic electrical defect and ongoing reliability issues.

Rear wheel lockup event in traffic while towing 24000lb 5th wheel on freeway. Vehicle was limped to a dealer, diagnosed as a transmission valve body failure. Repair took over 1 month stranding us over 1500 from home while on a trip.

I was driving in the high way and the vehicle started having issues and then it completely shut off and wouldn’t drive or anything in the middle of the highway and the dash said it was reducing power.

I have a 2023 GMC Sierra HD3500 6.6 Duramax. February of 2025 the valve body failed after 23,000 miles. The failure happened when the transmission had an extremely hard shift at 55 mph and then went into 5 gear limp mode. Computer through code P0700 and P0747. The P0747 is the code that tells you the valve body failed. When I took the truck to the dealer, they would not let me take the truck home because of the high risk of the transmission locking up and causing bodily injury, aka crash. Since the valve body was back ordered, I was warmed that it may be a month to get a replacement and install it. I finally got the truck back after 33 days. To add to the frustration, GM would not give me a loaner truck. They would give me a loaner SUV but that did not have what I needed out of a vehicle.

On Christmas Day 2025 my Tailgate flies open on its own and I see my cargo flying out and a piece of it bounced off my taillight passenger side braking the taillight and then when attempting to pull over my lane departing feature try’s to correct its self and I hit the median luckily at slower than I was going but enough to make a decent dent on front bumper

The engine oil drained into the radiator from a flaw in there design in which outrageously high labor cost for the owner of the vehicle they put a rubber house in the radiator in which leaked without any warning indicating that there was a problem with the oil nor the radiator coolant system. repairs are in the thousand and I as a consumer should have this matter resolved at no cost due to bad design cost they should have made a oil cooler with its own separation compartment like the transmission cooler because they are replaceing everything else what about the engine itself thats still going to be contaminated like all the replacement part, seal hoses,and radiator, coolant, and thermostat. How can just parts be contaminated but not the engine? They are just replacing things that costs alot. This is a drive train issue, there were no oil in the engine.