2018 GMC SIERRA 1500 Complaints

Spun main bearing in motor. Motor blown. It is available for inspection. GM mechanic inspected and quoted for new motor. Vehicle shut down going down interstate at 78 mph. No warning.

My engine and all electrical components including power steering and power brakes and all dashboard electrical will fail while driving. It is becoming more frequent and has almost caused an accident on numerous occasions to the point of not being able to drive safely on the highway any longer so now I only stay on surface streets and can't use for any out of town work. I usually do all of my own vehicle maintenance not been able to diagnose the culprit. Unfortunately I'm not able to afford the dealership diagnostic prices but open to any type of inspection.

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

Transmission just would not go them all of a sudden it jersey really hard in second gear an start to pick up speed..cold starts it change gear really hard in second gearc often times slipping then going into gear really violently.. need fix asap dealer has service once with the issue, change fluid an stopped a while ago now issue is back an worst then before.. 44,785 vehicle should not operate this way.4×4 awd trans starts at 6500 to replace an go up to about 13200 to replace

While driving my truck and making low speed turns the dashboard (including center console) cuts off, along with my power steering. The truck has also shut off completely making u-turns causing me to almost crash. This also happened while driving around 60mph on the freeway, the entire dashboard went out, loss of steering, and truck shut off, almost causing an accident. When it does happen, it will cut out in 1 second intervals and steering will work again for 2 seconds then cut out again for 1 second, this causing me to stall. There are no check engine lights, or service lights that stay on. However, I will get a message stating: You are memory setting 3 in the system (wording may be different). In some cases the stabilitrak light will come on, the park assist warning stating it shut off comes on dash, and trailer break. I have a full service AUL warranty and had vehicle checked at certified dealership and no codes were recorded. I replaced battery and the problem is still happening. This is unsafe and should be part of the previous recall as my symptoms are the same exact symptoms as the other 2018 recall.

The contact owns a 2018 GMC Sierra 1500. The contact stated that at start-up there was an abnormal ticking sound coming from the engine. There were no warning lights illuminated. The local dealer was contacted; however, the vehicle was not diagnosed. The contact was informed that the vehicle was out of warranty, and that the VIN was not under recall. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 17,000.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while attempting to accelerate from a stop, the vehicle failed to accelerate while depressing the accelerator pedal. No warning light was illuminated. The vehicle was taken to a local dealer, and the transmission was repaired under warranty. The contact stated that a year after the repair was completed, the failure reoccurred. The vehicle was not repaired after the most recent failure. The manufacturer was made aware of the failure. The failure mileage was approximately 94,600.

When I first bought my 2018 GMC Sierra with the 8 speed transmission it would shift hard from first to second gear. Then at around 58,000 miles my truck also started to have a vibration coming through the steering wheel around 45-55 mph. I took it to the dealership and they changed the transmission fluid and did a software update. I am now at 80,000 miles and my truck still shifts hard from first to second gear and makes a grinding sound when accelerating sometimes. I am afraid to drive my any long distances for fear of the transmission malfunctioning. I have not been back to the dealership since my truck is no longer under warranty. So the problem has not been reconfirmed by a dealer or independent service center or inspected by the manufacturer. There have been no warning lamps or messages or other symptoms. I hope that GM is held accountable for putting a faulty 8 speed transmission in my truck.

DRIVING 70 MPH ON [XXX] IN MODERATE TRAFFIC WHEN MY VEHICLE SUDDENLY SLOWED DRAMATICALLY AND BEGAN TO SHUDDER . I WAS IN THE MIDDLE LANE OF THREE WESTBOUND MARKED LANES AND WAS ALMOST HIT BY A DRIVER BEHIND ME WHICH HAD BEEN FOLLOWING TOO CLOSELY. THE CHECK ENGINE AND TRACTION CONTROL LIGHT CAME ON AND MY OIL GAUGE WENT TO THE HIGH SIDE. I EXITED ONTO [XXX] AND AT 40 MPH THE TRUCK WOULD SHAKE AND SHUDDER UNTIL I DROVE THE 6 MILES TO MY RESIDENCE. ON [XXX], I HAD THE VEHICLE TOWED TO LASH GMC DEALERSHIP IN JOHNSTOWN OHIO. ONCE THERE THE VEHICLE WAS DIAGNOSED WITH A FAILED LIFTER THAT BROKE INTO PIECES RESULTING IN A BENT ROD AND DAMAGED CAM SHAFT. THE DEALER RECOMMENDED FULL ENGINE REPLACEMENT DUE THE SEVERITY OF THE FAILURE. THE TRUCK IS A 2018 GMC SIERRA DENALI WITH ONLY 65,449 MILES ON IT. IT COST ALMOST $70,000.00 NEW AND THE REPLACEMENT ENGINE COST ME $14,221.96. I FEEL MY PERSONAL SAFETY WAS JEOPARDIZED IN THIS INCIDENT. SINCE THAT TIME I HAVE RESEARCHED THE 6.2 GMC ENGINE ONLINE AND HAVE FOUND REPORTS OF NUMEROUS SIMILIAR FAILURES AND INCIDENTS INVOLVING THE ENGINE IN QUESTION. I TRULY FEEL NHTSA SHOULD TAKE A STRONG LOOK AT THE ENGINE FAILURES INVOLVING THIS ENGINE AND FORCE GMC TO REPAIR OR REPLACE THE ENGINES IN QUESTION DUE TO THE SAFETY ISSUES INVOLVING THE ENGINES FAILURES IN TRAFFIC AND THE RISK ASSOCIATED WITH AN OCCURENCE. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My starter quit at 81,000 miles. It has always been a bit weak starting, but I have never had a starter go out on a vehicle at 81,000. I have replaced it, and the rebuilt starter is better than what was ever on this vehicle. I am also having problems with the transmission shuddering, shifting rough in low gear, and sometimes it reverses fast. Repair shops won't even touch the transmission. The dealership stated they couldn't get the problem to replicate the issues even though they know there are issues with the 8 speed transmissions.