2023 GMC Sierra 1500 acceleration problems

Filed Sep 16, 2026 · Acceleration, Fuel system · PA

The truck shut off and would just crank. It threw the code P129F. And wouldn’t start up until after 15 minutes.

Filed Sep 10, 2026 · Acceleration, Transmission · CO

Purchased above listed vehicle new in XXX. Immediately noticed a 'coolant' smell in cab. brought vehicle in for coolant smell issue on XXX and XXX. We were told that there was no issue until finally on XXX we were told the radiator needed to be replaced at OUR expense. XXX we received a letter from GMC advising the "engine coolant control valve" may fail. In XXX while driving on mountain roads (we live in [XXX]) the check engine light came on and while at 50 mph, the vehicle went into "limp mode" we lost power and speed was immediately reduced. We now know that a symptom of that valve failure is coolant smell in the cab of the car, a problem we had attempted to address with GMC from the beginning. We could have had a serious accident driving on a busy mountain road when this failure occurred. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jul 7, 2026 · Acceleration, Engine · MI

I was driving my family on the highway and my truck completely shut down. The screen flashed a warning and it slowly started decelerating. Thankfully I was able to make it to the shoulder of the road safely. Engine failure was a known safety issue with my model of truck, but I completed the L87 Engine Loss of Propulsion safety recall testing on 9/18/2025 and was assured my engine passed the testing and was not at risk for engine failure.

Filed Jun 3, 2026 · Acceleration, Transmission · IL

The truck side toy down shift and the accelerator was very high…. When I was going to park the reverse was not shifting…

Filed May 28, 2026 · Acceleration, Engine · WV

After driving my vehicle for a short period of time I stopped to go shopping. When I returned to my vehicle I started it as usual and the check engine light illuminated. I began driving and within 0.25 miles I received an info enter message that stated my vehicle would have reduced acceleration and to please drive safely. My engine fans became noticeably louder and ran the entire trip home (about 15 minutes). After pulling into my driveway I sat in the vehicle and listen to the fans continue to operate. Additionally, my OnStar system, WiFi, and navigation systems quit working. A P1098 Code was returned when using a diagnostic code device. Disconnecting the battery would cause the check engine light to extinguish and for the truck to operate without reduced acceleration; however, OnStar, navigation and WiFi would not work. After shutting off the engine and then restarting the check engine light would once again illuminate and the reduced acceleration message reappeared.

Filed Feb 2, 2026 · Acceleration, Engine · 8,496 miles · LA

The contact owns a 2023 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle shuddered while in first gear. The contact stated that the transmission sounded strained and shifted rough before slamming into gear. The vehicle was taken to the dealer; however, no cause for the failure was found. The dealer diagnosed the vehicle and determined that the vehicle was oversteering while turning to the right. The dealer replaced the valve and torque converter. On another occasion, while driving at an undisclosed speed, the vehicle accelerated independently. Most recently, a burned transmission fluid odor was coming from the front of the vehicle and entered the cabin through the A/C vents. There oil stains found on the ground on several occasions. The vehicle was taken back to the dealer and the valve body was replaced, the fluid levels were checked, and the transmission filter was replaced; however, the failure persisted. The contact called the dealer, and the dealer towed the vehicle. The dealer determined that the oil cap was loose. The vehicle remained at the dealer unrepaired. The manufacturer was made aware of the failure, and a case was opened. The failure mileage was 8,496.

Filed Jan 25, 2026 · Acceleration, Electrical · TN

This malfunction is ongoing and the dealership cannot fix the problem. The first time it happened in September 2025. I was driving down the road and the gauges started to go crazy. The screen on the dash said reduced acceleration. Then it said Service ESC. Then it said Service Traction Control. It would not let me go over 40 mph. I took it to the dealership and they told me I needed a valve body replacement. They installed the valve body and that did not fix the problem. It happened again and said reduced acceleration took over forcing me to pull over on the side of the road. The GMC dealership said to bring it in again but they could not reproduce the malfunction after driving for a week. It happens randomly. The third time this happened I was traveling up interstate 24 at about 70 mph. There were semi trucks around me when the malfunction happened and my acceleration and speed was reduced throwing the RPMs as high as they would go, and I was almost hit by a semi trying to move out of the way and onto the shoulder of the interstate I tried to accelerate to get out of the way of the semi truck but could not. I had to swerve over almost losing control of my truck. I informed the dealership that this had happened again and they asked me to bring it in. I did. They told me they were going to clean corrosion off of ground wires, and that should fix the problem. It did not. This keeps happening and I feel that the vehicle is not safe to drive. I do not know when it will happen again. I travel for a living and I feel the vehicle is unsafe to operate.

Filed Jul 5, 2025 · Acceleration, Engine · MI

Driving on the highway under normal driving condition, my check engine light came on and said service transmission. This then put the truck into "limp mode" and I was stuck going 60mph in a 75mph zone. Dealership scanned and found that the coolant sensor control flow valve is faulty. This part is in such demand for these vehicles that it is unknown when the part will be in.

Filed Feb 6, 2025 · Acceleration, Driver assistance · IN

While driving on the interstate, my vehicle started losing speed. I pulled over to the shoulder of the interstate and put in neutral so I could coast further to the exit ramp where I would be in a safer location. My vehicle has 14037 miles on the odometer and has now gone through 2 engines. It has always been serviced by GM.

Filed Sep 18, 2023 · Acceleration, Brakes · IN

Traveling at 70 mph on cruise control, tapped breaks to turn off, multiple warning lights flashed, vehicle lost power, and breaks with multiple messages including “Break system failure, top speed 62 mph”. I lost all breaking control on the highway and nearly crashed into other vehicles due to inability to stop. Was able to pull over, turn off vehicle, and turn back on, when the breaks were working again but the vehicles acceleration was very slow. Currently at authorized repair shop. When dropped off, there were 8-9 active codes.