GMC Complaints

My park to shift to park warning keeps coming on. It was replaced under warranty once and came on again comes and goes and dealership is not replace it again saying it isn’t tripping a code so it won’t get covered under the parts warranty.

purchased the vehicle in good faith, unaware that the check engine light was illuminated at the time of purchase and not informed that this indicated a serious mechanical or emissions-related issue. After purchase, the dealership repaired an emissions-related problem, and the check engine light was no longer present when the vehicle was returned to me. However, within three days of having the vehicle back in my possession, I began experiencing additional issues, including electrical malfunctions and abnormal noises coming from the front wheels. These problems caused the vehicle to feel unsafe to operate and raised serious concerns about its reliability and overall safety. Due to these concerns, I returned the vehicle to the dealership immediately.

I want to report the dealership, Hill GMC, in Newtown Square PA and the salesman, Vince Pace, that special ordered this vehicle for me in December of 2023 knowing full well that these cars had an engine problem. It was deceitful and cunning. I purchased a GMC 2024 Yukon Denali for $102,000 I am a senior citizen and I was taken full advantage of in this fraudulent sale.

While driving vehicle at highway speeds the vehicle shut down without any warning

2026 Sierra 1500 AT4 with 3.0L Duramax Diesel. Three major issues. 1. 2960 miles, thrust bearing failure caused low oil pressure and internal damage. Vehicle needs complete engine replacement. The truck is still at the dealer with no ETA on engine arrival and replacement. 2. Vehicle has severe electrical issues. battery replaced on second day of ownership due to over charge and smoking. The truck would randomly lose the ability to produce sound through infotainment system on start. This includes warning sounds and audible turn signal sound. Dealer said it’s caused by faulty Amp which was replaced. 3. The truck shut off (full system shutdown) and the transmission failed over to neutral while driving on the highway and failed to restart. Barely restarted on second attempt. Dealer has no idea why it is doing it. However the vehicle was throwing multiple code related to transmission module failure, brake module failure, transmission module failure, etc.

Unexpected rear wheel lock-up at 29000 miles. While engine braking from highway speed onto an off-ramp at approximately 50 mph, the rear wheels unexpectedly locked up. Due to prior rear brake actuator issues, I suspected the emergency brake had activated without my input. It was only momentary, and no fault codes or warnings were displayed. It happened again under the same circumstances two months later, with no fault codes. On May 9, 2025, the check engine light came on, and I scheduled service. The dealer addressed a recall regarding the transmission by installing software. In August 2025, I received a letter from GM regarding recall N242454440 for excessive wear in the transmission control valve, which was causing rear-wheel lockup. On October 31, 2025, while towing a small enclosed trailer at 70 mph on the highway with cruise control engaged, the truck suddenly decelerated, and I was nearly rear-ended by a semi-truck (no brake lights to warn them). The truck would not go over 50 mph unless I was going downhill. The transmission would not shift into higher gears. I returned it to the dealer, who checked the computer and found no record of the incident, so they said there was no problem. They informed me that the new software was designed to limit the truck's speed if a potential lockup was detected. This recall did not fix the transmission problem or the safety issue. It was simply a way to avoid costly repairs. There is a problem with the physical transmission valve that, for me, resulted in an extremely dangerous situation. The NHTSA needs to take this issue seriously and require GM to replace the prematurely worn valves in the affected vehicles.

Left rear parking brake actuator malfunction. The truck would brake unexpectedly. The brake would not completely release at times. Took it to the dealer on June 6, 2024 and they replaced the rear rotors and pads. I asked them if the parking brake actuator was faulty and may have caused the premature wear. They laughed and said no, it wasn't possible. On Aug 7, 2024 I returned the truck to the dealer with the fault codes C1114 & C060B caused by a failure of the parking brake actuator. It was impossible to use the emergency brakes when the codes were present. For several months after the repair, brake faults would appear and disappear randomly. Took it to the dealer, and they found nothing wrong. Electric-actuated emergency brakes should be illegal.

The service engine light came on while driving on the highway. We took it to a GMC dealership and they scanned to determine a short in the oil pressure sensor. This was replaced then during the final check they found metal in the oil. The warranty company made them tear the engine apart where they found multiple area where the metal was worn down including the gaskets, rings, and cylinders. The warranty company continues to fight us to cover the whole invoice.

The front camera stopped working, causing the safety systems to shut off. Codes U026A & U0078 "no communication failure". The camera was ordered and replaced.

Engine lifter spring failure followed by bent valve push rod experienced on or about 11/6/2025. Engine repaired/re-built at independent auto mechanic for a total of $6,450. Parts not available but have pictures. Depending on where this incident could have occurred (freeway, long trips, while towing (boat, horses), etc.) safety concerns include being stranded in traffic or remote areas. Engine lost significant power and wouldn't have been able to tow. Engine knock warning light.