general problems of the 2018 GMC Sierra 1500

Premature frame rot.

The truck started to vibrate or shudder . We are having to deal with replacing the transmission on our truck, which has only 45,000 miles on it. We have noticed numerous complaints about transmission problems with this model and the place that is replacing the transmission said they have had 3 customers in the last couple of months with the same issue on the same GMC model. This is a lot for our small town and area. Why hasn't GMC issued recalls ?.

The transmission would purge forward when shifting gears. The shifting was very rough. This vehicle had recently been in accident.

I have taken it in due to engine mounts 4 different times, transmission replaced and in October 2024 I took it in for issues I was experiencing like I had before my transmission went out. I did not get my truck back until almost Dec 2024 and that was due to there employee backing into the front end of my truck. So after all that my warranty was up Dec 24 2024 and then on April 16th 2025 I was driving my 2018 GMC sierra 6. 2l 1500 denali 129,600 miles at approx 30 mph it was late so the streets were empty and we started to hear a knocking or what I thought at the time was a very bad exhaust leak. We parked and then we started to try to make it home very slowly which we did and it was not making to much noise. The next day I called GMC and explained they said bring it in. I towed it there to be safe but it did start and still ran at very slow speed. They called me and said that the lift side rockers/ lifters 1 failed and it was stuck due to a misfire and that the engine would need to be rebuilt and sent me over some very vague break down which looked like a lump sum price. I requested and better break down and got a screen shoot and that when he said that’s the best they can do. There were no engine lights on or warnings nothing at all. It also just got serviced at GMC for an oil change on February 27th 2025 along with some air filters. Today is April 29th and still waiting for the service manage to call and see if they can do anything to help out instead of charging full price. I will attach pictures of the cost break down if possible. Thank you.

On February 10, 2025 the vehicle, a 2018 GMC sierra, caught on fire while parked in the driveway of my home. The vehicle had last been driven earlier in the day with a return to home at approximately 12:45pm. At approximately 7pm I heard a loud pop outside of my home and saw orange light coming through the front windows. Upon going outside, I found the rear of the vehicle engulfed in flames. The fire was coming out around the remains of the license plate, up and around the rear bumper on the left side, and progressing up the tailgate and window hatch on the bed cap. The fire progressed forward over the next few minutes as the fiberglass cap burned. Eventually the fire penetrated the front window of the cap and rear window of the cab and began burning the interior of the cab. About the time the fire department arrived the fuel tank ruptured and began spilling gasoline onto the ground beneath the vehicle. The fuel tank was approximately 7/8 full. The fire department eventually extinguished the fire, but the vehicle was a total loss. My wife and I had been in close vicinity of the vehicle during the afternoon hours and had noticed nothing unusual. There had been no unusual issues with the vehicle during the prior drive, which had been a 5 minute drive to/from a local home supply store. There was collateral damage to the front of my house as a result of the heat from the fire, as well as damage to the driveway. If the vehicle had been parked in the garage it is resonable to assume that the house would have been destroyed.

I purchased my sierra in 2021 and 2 weeks after purchase I got a warning for service stabilitrk and another for trailer brake system. This is very very annoying and also has my abs light on. My next issue is a code u510 for active grille shutter assembly. Please fix these issues as they are very common and unsafe. Not to mention as much ad I paid for this truck.

Vehicle is shaking at highway speeds.

Ac condenser went out on my vehicle with 100,000 miles, lots of reviews online stating this is a known problem but yet there is no recall. Torch converter going out at 80,000 miles.

Like many of the 2014 and 2015 models, my vehicle has experienced the exact same failure in the radiator due to the thermostat over cycling. There is already a TSB for those models, yet gm changed nothing in the subsequent models and the problem persists.

Sunroof shattered while driving on the interstate.

In short, the moonroof of my vehicle spontaneously exploded into a million pieces one morning while driving.

Received an error on the dash saying "service brake assist". At the same time the brake pedal became very stiff and braking power was decreased significantly. I have received this same message and brake pedal stiffness with reduced braking power three times in the last 4 days.

Informant system and instrument clust/panel starts to change with nothing be clicked. Starts to phantom change everything which is deters from paying attention to actual driving becoming a safety hazard. Dealership has tried to update the software and still does not work.

Air conditioning condenser failed at about 48,000 miles. Seems to be a common problem that is a design defect.

Constantly getting “service trailer brakes system “.

My rear back heated window on the passenger side popped and shattered the window while I was sitting in the passenger’s seat waiting for my husband. The truck smelled like a sweet wire smell and then I heard a loud pop. I looked back and the back window panel was shattered. I do see that there were recalls on some of these windows.

The radiator developed a leak on the drivers side. This caused a loss in antifreeze.

My rear driver side door electric harness failed only two years after owning vehicle. This disables everything, including the side airbag putting passengers at risk. Most recently (2024), my radio harness failed causing all functions regarding infotainment system to be obsolete. Multiple electric issues and no recalls to be seen.

After cold starts when accelerating the transmission slips from 1st to 2nd and throws your body forward. After that first gear change it doesn't do it again until another cold start. Around 34000 miles I am getting a rumbling vibration through the dash and steering wheel when holding speed between 35-75 mph. The rpm guage will jump slightly and it will feel like going over rumble strips. Acceleration is very weak at times. Sometimes its ok. There has to be something done with these torque converters and transmissions by gm. Unacceptable for a 40-50k dollar truck!.

Condenser on ac leaking at same location as the 2014-2017 my. Warranty was out due to mileage but truck is only 2 years 3 months old. Blowing warm air when ac was turned on.

I have had my truck in the shop several time for the rear springs they finally replaced the springs and I am having trouble again my warranty is out but I took it to see if gm would take care of the problem but they don’t seem to want to do anything and I no my vehicle is not the only one that has had this issue.

The vehicle operates unpredictably when pressing on the gas pedal causing unsafe driving conditions. When pressing the gas pedal, any one of the follo^wing conditions may occur. 1. ) sometimes the rpm's decreasea. 2. )sometimes the transmission hunts several times. 3. ) sometimes the vehicle speed surges. 4. ) many times the engine hesitates for a long period before the rpm's increase. This unpredictable operation is more apparent when the engine is loaded like going up hills and especially when heading into strong winds. The unpredictable operation is extremely unsafe when driving on ice covered roads. This vehicle is also considered an "off-road" series vehicle. This unpredictable operation is very unsafe, even dangerous, on aggressive trails. When driving in steep trails, drivers require feedback from their vehicle especially how the vehicle or engine responds as the gas pedal us depressed.

My vehicle is hacked anytime I am driving the vehicle I am not in full control. The vehicle steers itself left or right while driving, the brakes are always on while driving sometimes braking harder but always on. The infotainment system has many glitches. This vehicle has been back to the dealership more than 15 times has been out of service over 35 days gm even flew a engineer/tech to inspect the vehicle and says they couldnt find anything. Therefore this vehicle is hacked there are so many issues and glitches and the fact that the truck only acts like this when I am driving no one else. Like it can be turned on and off instantly. I have tons of videos pictures and supporting documents backing this. I need help this is a serious issue and there is so much more to it than I can type here someone please get ahold of me to help or point me in the right direction. This vehicle will be returned to gm soon as they are doing a vehicle replacment per all the issues but this needs further attention because if this can happen to me it can happen to anyone . Please help.