GMC Complaints

The contact owns a 2026 GMC Sierra 3500. The contact stated that while driving at 35-40 MPH on the interstate and towing a loaded trailer, the vehicle experienced reduced braking performance. No warning lights illuminated. The local dealer was contacted and informed that the brakes performed differently. Additionally, the dealer stated that the transmission was not downshifting. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 500.

I am reporting a safety defect involving my 2025 GMC Hummer EV 3X (VIN: [XXX]). On XXX at approximately 18,880 miles, I first presented the vehicle for steering/alignment, suspension, and handling concerns. As of this complaint, the vehicle has approximately 26,840 miles. I have driven nearly 8,000 miles while repeatedly reporting unresolved safety concerns and transporting my two children (ages [XXX] and [XXX]) because I had no practical transportation alternative. Following warranty repairs, including rear control arm replacement, the vehicle developed a severe pull to the right that did not exist before repair. It requires constant steering correction to remain in its lane, and Super Cruise can no longer reliably maintain lane position. Premature and abnormal tire wear has continued throughout the unresolved alignment condition. The vehicle has undergone six warranty-related service events at two authorized GM dealerships. Despite repeated repair attempts and two direct escalations to General Motors requesting repurchase, the only resolution offered has been additional diagnostics and repair attempts. A courtesy loaner was not offered until the sixth service event, after months of unsuccessful repairs, thousands of miles of continued operation, lost wages, and repeated travel. The vehicle also continues to experience water intrusion despite warranty repairs. Rainwater enters the passenger compartment, leaving a persistent musty odor and raising concerns regarding mold, mildew, occupant health, and interior deterioration. I have filed a Georgia Lemon Law claim after exhausting GM’s internal process. I also documented my experience publicly. Posts received approximately 17,500, 48,900, 60,100, and 24,800 views. Many GM owners described similar repair experiences and unresolved INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

"Steering Assist Is Reduced – Drive With Care" warning appeared while the vehicle is in motion. This may require increased steering effort and could affect a driver's ability to respond to changing traffic conditions. Any steering-related warning that appears unexpectedly while driving deserves serious attention. P0128 code was shown. The cause was a faulty thermostat housing assembly and needed to be repaired. This is an extremely common issue in this vehicle across many years and needs to be investigated.

Catastrophic engine failure while traveling 40 mph. Dealership diagnosed as cylinder walls being scorched and rods blown through. No warning signs existed - just had a loud thud before the check engine light started flashing and grinding sound started coming from engine.

the flexible steel cable connecting the seat belt to the seat separated and broke resulting in no way to use the seatbelt/connecting the seat belt to the connector on the seat.

These tires are not safe for off-road to highway use. After transitioning to the highway from a gravel driveway, I noticed that rocks were stuck in the treads. A significant about of rocks became dislodged and start to contact my vehicles underbody steps. I feel as if this can create significant and costly problems for the vehicles that are following close or perhaps behind in any manner. Large rocks and what I would classify as mini boulders are often found lodged in the tread and don't come out till they are picked out or fly out.

When I’m driving on the highway, I get a message on my dashboard saying steering assist reduced, drive with care. I have taken to the GMC dealership and they will not cover this repair even though it would be covered for 2021 GMC. When this happens, my car makes a loud noise and my steering wheel does not feel right. I do not feel safe.

On XXX, I was towing my camper to Copper Center, Alaska from Palmer, Alaska when my truck experienced a full transmission shut down which put the truck into "Reduced Power Mode". We descending down the road right next to Victory Bible Camp (64741 Victory Rd, Sutton-Alpine, Ak 99674) when the exhaust break turned off and the truck decreased power and the Check Engine Light illuminated. The Diagnostic that was produced by OnStar revealed 3 different codes. ( P0700 TCM, P0747 Pressure Control Solenoid A is stuck in the "ON" position, C116b faulty brake pad wear sensor.) I called GMC of Palmer and GMC OnStar advisor, both informed me that the truck needed to be towed. My safety concerns is this.... I had minimum cell phone signal and not a gas station or service station within MILES. I was on the side of the Alaska Highway 1 which is a major thoroughfare for traffic going to and from [XXX]. Thankfully there were a few kind folks that pulled over to offer assistance. My truck is a 2023 GMC Sierra 2500hd with only 26,262 Miles on it. I purchased this vehicle XXX. (It Still has the Temporary Tags on it.) If had been in a different part of Alaska when this transmission failed to function properly then we could be talking about a life or death situation. Especially, if my child was with me. I was hauling my camper that weighed ATMOST, 7,000 pounds. This is less than 40% of the trucks ability. I feel that this could put someone into a dire situation had they not had the experience with emergency situations like I have had. (Prior Military Service). I have also filed a complaint with GMC Motors. Case# XXX. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The Screen calls my own phone number and hangs up over and over if I just ended a call. I am not able to use any part of the screen afterwards such as my map. It stays like that until I disconnect the Bluetooth and wifi from my phone while trying to drive. Safety issue!

Steering assist reduced is the warning. The AC will no longer work and the fan runs constantly. From what I’ve read, it is a popular problem for Acadia owners and the thermostat and sensor has to be replaced. We have not been able to replace ours yet because of the cost.