2025 GMC Sierra 1500

The contact owns a 2025 GMC Sierra 1500. The contact stated that while driving approximately 5 - 10 MPH, the vehicle went into LIMP Mode and failed to properly accelerate, and the transmission unexpectedly downshifted. There was an electrical malfunction, which caused the transmission to downshift. An unknown message was displayed on the instrument panel. The contact stated that the network was not operating at the correct voltage due to the wiring harness. The engine light illuminated after the failure. The vehicle was towed on two occasions to the dealer to attempt to duplicate the failure. The dealer was unable to determine how to repair the vehicle. The vehicle was driven to the dealer in LIMP Mode. The manufacturer, General Motors, was contacted by the dealer, and the contact also reported the failure to the manufacturer. A General Motors service engineer had inspected the vehicle. The failure mileage was approximately 34,637.

Turned on vehicle and an alert popped up "Brake system control module malfunction", limited speed to 43 miles per hour, no power breaks worked. I have had no issues with brake system for the first 11k miles. I contacted my local GMC dealership (Banks Chevrolette in Concord, NH) and was told that I would not be able to get an appointment until the 2nd week of November. I told them this was a break system issue covered under warranty and they told me I was welcome to DRIVE to their dealership (14 mi away on INTERSTATES and CITY STREETS) and wait to see if there was any time to plug it in, but they would not guarantee there would be time on their end. I spoke with the service manager and was told the same and that his advice was to "not drive it until November". I was able to take the truck to a shop in town 2 mi away , and they printed off the following codes: P25A U160F U1610 U2418 U2419

Super cruise was engaged on I-95 and attempted a lane change. Another vehicle was in a position along side my vehicle that would have resulted in an accident if I had not noticed it and manually grabbed the steering wheel to override the super cruise. I have an appt with the dealer next week. The vehicle is also is occasionally displaying a "service driver assistance system" message

I was driving in town when all lights on the dash lit up, and I mean all of them. I was approaching a traffic light in low traffic in the 20-30mpg range. I went to apply the brakes and almost had none. If I was going to estimate how much braking was available, it would be in the 10% range. I drove at 20mph to the nearest dealer. They verified the issues. They reflashed the computer, drove the truck afterwards, and pumped the brakes. They told me they recommended an immediate master cylinder replacement. They had seen this twice already in the month of August. Both times prior to mine the reflash initially worked, but the problem returned within a week, and the master cylinders had to be replaced. The master cylinder replacement was a 2600 repair.

When updating the vehicle as prompted by the entrainment system the next day when attempting to start the vehicle it did not start. Vehicle had to be jumped then 6 warning lights came on and disappeared shortly after driving.

On XXX my 2025 gmc sierra 6.2L v8 engine experience catastrophic engine failure with no preexisting alerts or warnings. It was towed to Baglier gmc in [XXX] on XXX and is currently awaiting diagnostic evaluation. Upon restarting the vehicle after failure, the engine light did turn on. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

So I spent many months trying to aquire a GMC Sierra Denali and with all the issues with the 20 - 24 6.2 engines we were assured by the dealer that all the issues were resolved with the 2025 6.2 models. So we spent big to aquire an 2025. So I bought one new. My truck had 8000 miles on it with 2 oil changes. So we booked a trip to [XXX] at considerably a large expense and loaded up our Harley's on my light aluminum trailer, less than 3.5k pounds and headed that way from [XXX]. We made it to [XXX] and spent the night. Next morning we were heading to [XXX] and the truck blew up on the XXX. We were pulled over on a very busy hi way and had to get truck and trailer towed back to [XXX]. We were stuck there for 3 days while GMC installed a rebuilt motor in my 83k truck and totally missed our entire vacation. On line it said GMC would cover hotel and 40.00 dollars a day food. I am so disgusted after being reassured that GMC had fixed the 6.2 and putting our life in danger blowing up on a major highway, and afterward GMC only gave us 200. For our inconvenience. Our room alone was more not counting the money lost on out trip accommodations. I am so completely disappointed with this truck that we bought new and spent more than we ever had on a vehicle, and am afraid of ever taking another trip in it. How can GM be allowed to do this to people. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Safety Complaint – 2025 GMC Sierra 1500 Tailgate While driving our 2025 GMC Sierra 1500 and towing a trailer, the tailgate unexpectedly opened and dropped down while the vehicle was in motion. No one touched the tailgate button, key fob, or any other controls to activate the tailgate. We were unaware that the tailgate had opened. When we made a turn, the trailer contacted the tailgate and crushed/damaged it. This occurred without any intentional activation of the tailgate release. We believe this presents a significant safety concern because an unexpectedly opening tailgate while driving, especially while towing a trailer, could result in property damage, loss of cargo, or a more serious accident. We are requesting that this issue be investigated to determine whether there is a defect with the tailgate latch, release mechanism, or electronic controls on the 2025 GMC Sierra 1500.

FROM DEALER ASSESSMENT Concern - CUSTOMER STATES WHEN VEHICLE IS ACCELERATING THERE IS A RATTLE Correction - test drove and was able to duplicate rattle/knocking from the engine. checked oil level and condition verified both are good. checked for bulletins and followed 23-NA-170. compared vehicle noise to noise is video and noise is nearly identical. removed oil filter and inspected for debris, found heavy amounts of metal debris present in the filter. performed crankshaft end play mesasurement and found that the crankshaft end play is way over spec at 1/4 of an inch. recommend replacing the engine assembly per bulletin Parts) 1x ENGINE 2x (S)GASKET $0.00 $0.00 6x (S)BOLT 1x BOLT 1x exhaust pipe connector gaskets both sides $0.00 8x (S)GASKET 1x fuel feed pipes all $0.00 1x (S)SEAL KIT 1x (S)GASKET $0.00 1x (S)SEAL 1x W-(S)RADIATOR $0.00 1x (S)HOSE 1x coolant $0.00 1x oil filter 1x oil $0.00 Approved 2026-08-18 Labor: $0.00 Parts: $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 Subtotal Line B: $0.00 *Subtotal is before Shop Charge and Taxes

ENGINE STARTED KNOCKING AT 18K MILES AND TOOK TO DEALER AND THEY FOUND METAL IN THE FILTER AND INSTALLED A NEW ENGINE AND ALSO REPLACED THE MIDPLATE GASKET ON THE VALVEBODY DUE TO A HARSH DOWNSHIFT WITHOUT CODES IN THE SYSTEM THIS ENGINE IS GOING ON 2K MILES AND IT SEEMS TO BE FINE NOW BUT THE PROBLEM WITH 6.2 WAS ONLY SUPPOSED TO BE ON THE 21-24 MODELS AND MINE IS A 25 MODEL AND ALREADY HAD A REPLACED AND NOTHING FROM GM WAS SAID TO EXTEND THE WARRANTY ON THIS MODEL AND POWERTRAIN