GMC Sierra Complaints (2015)

916 consumer complaints on file.

#11774246October 28, 2026
SERVICE BRAKES, HYDRAULIC
The contact owns a 2015 GMC Sierra 2500. The contact stated that while driving 55 MPH uphill, the vehicle went into LIMP Mode and the vehicle hesitated. A dealer contacted. The vehicle was taken to a dealer and was diagnosed with brake booster failure. The brake booster was replaced and the vehicle was repaired. The manufacturer was notified of the failure and informed the contact that the vehicle was not under recall. The approximate failure mileage was 131,208.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11772673October 21, 2026
POWER TRAIN
The 6-speed automatic transmission (6L80) developed a severe shudder during normal driving. A service center diagnosed the problem as torque converter clutch failure; the torque converter sheds metal debris through the transmission, so the transmission now requires a full rebuild quoted at approximately $6,000. The failure occurred at approximately 92,000 miles in October 2026 (incident date is approximate). This is a widely documented failure pattern on GM 6L80 transmissions. Loss of reliable power delivery from the transmission is a safety concern. No crash, no injuries, and no fire occurred. The vehicle is available for inspection upon request.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11766980September 25, 2026
ENGINE
In August, 2019, at 93,672 miles, GM covered a lifter failure on our 2015 GMC Sierra, V8 AFM engine. Only the left side was repaired. Now, in 2026 at 130,000, the right side has the same issue and needs repair. The estimate to repair is $16,697. This is a known issue and a safety concern.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11766154September 22, 2026
POWER TRAIN
The transmission Started Shuddering, it would slip occasionally and slipped badly when i was driving in rush hour traffic in the middle of a left turn. had no power for several seconds then it finally reengaged. The shuddering got worse and worse to the point i took it to a transmission shop to look at it and they said i needed a replacement transmission unit. I did get a replacement unit, the whole process was extremely unpleasant. The previous unit was sent as a core to be remanufactured. The company that i used to get a remanufactured unit is Fraser Transmissions. No warning lamps appeared prior to the transmission acting up.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11763463September 10, 2026
ELECTRICAL SYSTEM, POWER TRAIN, STEERING
Power steering seems to be lost for a second or two at low speeds turning. Happens multiple times a day.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11760877August 31, 2026
ELECTRICAL SYSTEM, STEERING
My 2015 GMC Sierra 1500 recently started having all the symptoms under GM internal recall number 18289. I lose my power steering briefly and the electronics turn off momentarily. I lose dash, AC, radio and GPS. It comes back on within a second or two and only does this during low speed turning. I ran my VIN but it does not show under this recall despite having the correct Make/Model/Year. It is currently at the shop because it isn't safe to drive and I was hoping I could get a reimbursement for the repairs. NHTSA Campaign Number: 18V586000 (GM's Internal Number: 18289)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11759074August 24, 2026
SERVICE BRAKES, HYDRAULIC:PEDALS AND LINKAGES, VEHICLE SPEED CONTROL:ACCELERATOR PEDAL
The contact owns a 2015 GMC Sierra 3500. The contact stated that the brake pedal and accelerator pedal lifted while depressed, causing the engine to rev. There were no warning lights illuminated. The dealer was contacted and made aware of the failure. The vehicle was not taken to the dealer to be diagnosed or repaired. The manufacturer was not informed of the issue. The failure mileage was approximately 37,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11758571August 21, 2026
STRUCTURE
See attached document for complaint.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11758124August 20, 2026
ELECTRICAL SYSTEM
From time to time since I got the vehicle, the lights flicker inside and out. I've had the alternator changed but it continues. Then when pressing the lock button on the key fob the horn sounds as if it has a shortage. Sometimes its loud and sometimes it's barely heard.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755314August 6, 2026
POWER TRAIN
My 2015 GMC Sierra 1500 SLE has the 6L80 transmission. While traveling on the interstate with my fiancé, the transmission failed. It was towed to a garage and they informed me that it needed to be replaced.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11749832July 12, 2026
VISIBILITY/WIPER
my rear window defrost turned on when i auto started my pickup. i realized it was on after about a half hour and looked back and my drivers side of the rear sliding window was shattered completely
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11748839July 7, 2026
SERVICE BRAKES
When backing up, either on a hill or flat surface, the brakes fail to stop the vehicle. There is a pulsing sensation with the brakes due to failure of the vacuum. The brake pedal also becomes impossible to depress. No warning lights appear when this occurs.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11742780June 8, 2026
SEAT BELTS
The contact owns a 2015 GMC Sierra 1500. The contact stated that while driving at 25 MPH, the front driver's seat belt completely failed. The lap belt portion came apart, causing the chest strap to loosen. Upon inspection, the contact observed that the steel anchor cable bolted to the floor had separated. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was approximately 153,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11740204May 26, 2026
ELECTRICAL SYSTEM, POWER TRAIN, UNKNOWN OR OTHER
For no apparent reason the truck goes into “low power mode” and gives off code p2138 often happens around 30-35 mph. Have had it happen to me also around 45 mph also. I have replaced sensors and parts to which a month or so goes by and it happens again.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11738356May 16, 2026
SERVICE BRAKES
Vehicle doesn't stop in low speeds
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11737603May 13, 2026
ELECTRICAL SYSTEM:BODY CONTROL MODULE/BCM, SERVICE BRAKES, HYDRAULIC
The contact owns a 2015 GMC Sierra. The contact stated that while driving at an undisclosed speed and also while the vehicle was parked, the ABS and stability control warning lights would unexpectedly illuminate. The vehicle was taken to an independent mechanic, where the warning lights were cleared. The contact was informed that if the failure recurred, the EBCM and BPMV would need to be replaced. The vehicle was not repaired. The contact stated that the failure recurred. The vehicle was then taken to the dealer, where it was diagnosed that the EBCM and BPMV had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 90,100.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11732442April 20, 2026
ENGINE
Active Fuel Management Miss firing Idle rough Shaking Loss of power #7 cylinder loss of all compression Bad fuel mileage Skipping
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728045March 30, 2026
AIR BAGS
The contact owns a 2015 GMC Sierra 1500. While traveling on a two-lane highway at approximately 55 MPH, another vehicle suddenly turned into the contact's lane, resulting in a severe frontal "T-bone" collision. The force of the impact caused the other vehicle to be propelled into a ditch, while the contact's vehicle remained on the roadway. Despite the significant nature of the crash and the speed involved, no air bags deployed. The dealer was notified of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 218,000.
Crash:
Yes
Fire:
No
Injuries:
0
Deaths:
0
#11726316March 23, 2026
STRUCTURE:BODY, SUSPENSION
Truck started to make loud clunking noise when driving taken it to two shops and wrong parts were installed as stated below. Bought from a used car dealership and they sold it as is now with the wrong parts.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11726320March 23, 2026
STRUCTURE:BODY
Bad paint used by manufacturers that causes frames to rust out.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

← Back to GMC Sierra