GMC Complaints

June 29, 2025, Driving on the St. Francis loop in Amarillo, TX, brake lights start flashing, the warning sounds happening, no brakes. I had already slowed down to 35-45 mph due to road construction ahead. I weaved through the cones and as soon as possible, hit the ditch and then coasted to a stop. (I didn’t think about the emergency brake, in my panic.) I turned the vehicle off and called my husband. I decided that I wasn’t pulled over far enough over in the ditch, so I started the pickup again. The lights and warning signals for the brakes were gone and when I pressed on the brake pedal, there were brakes again. I drove home at 35 mph, knowing I could use the emergency brake at that speed, if needed, and had brakes all the way home. GMC Bender repaired truck. After driving approximately 3 miles since repaired, our daughter took the truck to Grease Monkey. She was at the garage door; employee said the pickup didn't need an oil change. She backed out and didn’t have brakes (no warning lights or sounds) and as the truck continued backing, it hit the Grease Monkey sign at the east end of their lot and broke it, knocked the sign over. An employee walked over to see what happened, she told him that she didn’t have brakes. He sat in the pickup seat and pushed on the brakes and said, yes, you don’t have brakes! The police were called, and the officer who showed up took pictures, gave us his card, talked with my husband and talked to the Grease Monkey boss. August 6, 2025, I called GMC Bender Service Department (11 mins. 8 secs.) I told them what had happened. They sent a tow truck to bring the pickup back to their shop. September 16, 2025, my husband texted me saying GMC Bender said that the pickup shows another EBS Modulator Fault. No new parts… used one would be $1293 installed. A week to get it here, no guarantees. There's more details, but the vehicle cannot be repaired to guarantee brakes will work properly. Please help us know what to do next.

A small drip started approximately 18 months ago from top middle of left side window in rear slider. It was first mistaken as blow by from car wash. Leaking slowly progressed to dripping down middle of both side windows in rear sliders. Leaking progressed to drops coming from under headliner then dropping on side portions of rear slider. It then would drip onto seat or behind seats. Leakage was consistent with TSB 18-NA-383 as well as 20-NA-142 and 24-NA-103. In discussing with dealership, they recommended likely microfractures and sealant process called for in bulletins would likely resolve matter. As due diligence, spoke with independent glass shop to confirm. Glass shop indicated would not know until physically checked cracks/source of leak and looked for damage but based upon photos it appeared to be several frame fractures consistent with bulletins. I arranged rear slider replacement through independent shop. Upon pulling OEM slider, numerous stress cracks and fractures were noted. These included stain marks from water intrusion. Photos included showing original leaking as well as sample of cracks in original OEM plastic frame portion.

The contact owns a 2019 GMC Sierra 1500. The contact stated that while at a red traffic light, the vehicle accelerated unintendedly, and the vehicle shuddered with an abnormal dinging sound coming from the vehicle. The message "Transmission Hot - Idle Engine" was displayed on the instrument panel. The vehicle was taken to a dealer where it was diagnosed and determined that the transmission was slipping, overheating, and that the transmission needed to be replaced. The contact researched and became aware of a recall; however, the VIN was not under recall. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 126,098.

On July 28, 2026, while traveling on vacation with my family, our vehicle experienced a catastrophic engine failure. There were warning lights displayed for 30 seconds prior to the engine failure. On July 23, 2026, one day before taking the vehicle to the dealership, the following warning indicators appeared on the dashboard and then disappeared: “Service ESC,” “Service Traction Control,” and a flashing engine light. We took the vehicle to the dealership on July 24, 2026, because we wanted to be proactive and ensure that the vehicle was safe to operate. The dealership inspected the vehicle but reported that no diagnostic trouble codes were identified and no issue was found. We picked the vehicle up from the dealership on the evening of July 27, 2026. On July 28, 2026, while traveling on the highway approximately 2.5 hours from home, the same warning messages appeared on the dashboard again. Because we were traveling at highway speeds and vehicle speed management was becoming an issue, I immediately exited the highway and stopped in a parking area. I placed the vehicle in park, at which point the engine began idling extremely rough. I could feel the vehicle shaking while sitting in the driver's seat. I exited the vehicle to open the hood, but before I was able to do so, I noticed gray smoke coming from the exhaust. We located a GMC dealership approximately two miles away. Because of the vehicle's condition, we drove there slowly on the frontage road at approximately 15 mph and dropped the vehicle off for diagnostic inspection. The GMC dealership subsequently diagnosed the vehicle with catastrophic engine failure and recommended that the engine be replaced. The vehicle remains at the dealership and is available for inspection.We made a reasonable effort to have the vehicle inspected before our trip because we were concerned about the warning indicators and wanted to ensure that the vehicle was safe to travel.

The vehicle stopped dead in traffic and would not restart. No warning lights. This is a huge safety hazard. Had to be towed to a dealership. The dealership and other diesel shops said the issue is a known catastrophic CP4 fuel pump failure. The fuel pump shreds and metal shavings are found throughout the fuel system. Requires a full fuel system replacement...quotes have been obtained from GM dealership and local diesel mechanics, ranged from $15,000-$17,000. There is a known fix and could have been solved by replacing the fuel pump with an alternative one, without putting us in a dangerous situation. There is also a settled class action lawsuit directly associated to this fuel pump and issue, however the vehicle was purchased in GA and therefore not included. Based on the VIN the truck would be included if sold within a qualifying state. GM corporate and dealers know about this problem and the safety risk, but are not even suggesting the fuel pump conversation as a repair. They are putting customers in dangerous situations and leaving them with high bills.

transmission shift hard and slipping. When step on gas to go faster transmission shifts really hard like going drop on ground. Sometimes wont shift at all only goes up to 69 till left off gas and then transmission will shift. Start happening with about 10000 miles on truck and GMC said this is normal. Now need a torque converter and shift module in it.

Head gasket failure and overheating. After fixed, power steering has just failed during driving. Will have to have it towed to shop

On August 6, 2026, I was driving my family up to Whitefish Mountain Resort (a steep mountain road to a ski resort) for dinner when the ESC warning and "Brake System Failure" warning appeared. I immediately attempted to pull safely to the side of the road. When I pressed the brake pedal, the vehicle did not respond normally. I pushed the brake pedal as far down as I could and had essentially no braking ability. Because we were traveling uphill, the vehicle eventually rolled to a stop. When my brother came with his car he had a vehicle scanning tool. He hooked my vehicle up to it and the tool displayed diagnostic codes P25A2 and P3499. This was an extremely serious safety event. Had we been traveling downhill, approaching an intersection, or driving in heavier traffic, the outcome could have been catastrophic.

While driving my 2018 GMC Terrain, the vehicle suddenly displayed an “Engine Power Reduced” warning and the brakes became extremely hard to press. The vehicle experienced a sudden loss of normal power-brake assist while it was in motion, creating a serious safety risk because significantly greater pedal force was required to stop the vehicle. I was able to pull over safely. After stopping, the vehicle would crank but would not start. The vehicle was towed to a GMC dealership for inspection. The dealership documented that the vehicle had a suspected failed/broken vacuum pump, a damaged exhaust camshaft, and a damaged exhaust camshaft actuator. The dealership subsequently documented that the engine was severely sludged and stated that the sludge caused the vacuum pump to fail, which then caused the exhaust camshaft to twist and damage the exhaust camshaft actuator. The dealership’s written diagnosis recommends replacement of the exhaust camshaft, exhaust camshaft actuator, vacuum pump, and associated one-time-use parts. The dealership has also documented diagnostic trouble codes P0014 and P0017. The failed vacuum pump and related components should be available for inspection upon request. The vehicle has been inspected by a GMC dealership, which has documented the suspected vacuum pump failure and resulting engine damage. The sudden loss of power-brake assist occurred while the vehicle was being driven and created a potentially dangerous loss of braking capability. I am reporting this because I believe the failure of the vacuum pump and resulting loss of brake assist may represent a safety-related defect requiring investigation, particularly because the vehicle experienced a hard brake pedal without prior warning.

The contact owns a 2026 GMC Yukon. The contact stated that while walking alongside the rear end of the parked vehicle, the hands free function of the lift gate opened up unintentionally, no warning lights were illuminated. The contact was not injured, however expressed concern for safety as the lift gate will open without user consent while walking along the rear end of the vehicle. The local dealer was contacted however the vehicle was not diagnosed as the contact was advised that the vehicle was manufactured with the feature. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 60.