Complaint volume
290 consumer-submitted complaints are matched to this model year. Treat the count as a research signal, then read the actual summaries for repeated symptoms.
Complaint records
2018 GMC Sierra Complaints
290 consumer-submitted complaints on record for the 2018 GMC Sierra, grouped by component category.
290 Total complaints
10 Crash reports
1 Fire reports
5 Injury reports
Complaint data reflects consumer-submitted reports. A complaint is not proof
of a defect, recall, or manufacturer fault. Enriched severity fields come
from official bulk records when the complaint can be matched by ODI number.
Buyer interpretation
How to use these complaints before buying
Complaint records are most useful when they turn into inspection points, seller questions, and comparison checks against nearby model years.
Pattern to inspect
The most common categories are power train, engine, service brakes. Use those categories as a test-drive checklist instead of judging the vehicle from the total count alone.
Severity flags
Enriched records include 10 crash reports, 1 fire report, 5 injury reports, and 0 fatality reports. These fields come from complaint records and should be read in context.
Mileage clue
Mileage is available on 121 complaints, with an average reported failure mileage of 45,272 miles. Compare that with the mileage on the listing.
Questions to ask the seller
- Have you had any problems related to power train, engine, service brakes?
- Can I see recent maintenance and repair records?
- Has the vehicle ever been towed, involved in a crash, or repaired for the same issue twice?
- Can we also check the recall record for this 2018 GMC Sierra?
Used-car checklist
Use these complaints before the test drive.
Build a buyer checklist to turn these issues into questions and inspection points.
2018 GMC Sierra
Build buyer checklist Compare with other years Sends year, make, and model to pre-fill your checklist.
How severe are the 2018 GMC Sierra complaints?
10 Crash
1 Fire
5 Injury
0 Fatality
12 Towed
3 Medical attention
What are the most common 2018 GMC Sierra complaint categories?
POWER TRAIN 85
ENGINE 30
SERVICE BRAKES 15
UNKNOWN OR OTHER 14
ELECTRICAL SYSTEM 11
ELECTRICAL SYSTEM,SERVICE BRAKES 10
POWER TRAIN,ENGINE 10
STEERING 10
AIR BAGS 6
SEAT BELTS 4
290 total complaints on record
Latest complaints
| Date | Component | Summary | Severity | Mileage |
|---|---|---|---|---|
| May 2025 | POWER TRAIN,ENGINE | GM has discontinued a critical engine belt on the 2018 GMC Sierra 1500 5.3L eAssist. This makes the truck undrivable and unsafe to own, even though the vehicle is still under financing and only 7 years old. There is no available part, and no alternative has been offered by the manufacturer. | Crash: No Fire: No | Unknown |
| May 2025 | ELECTRICAL SYSTEM | Apparently, GMC began using soy-based wire coatings approximately 10 years ago. The wiring harness on my vehicle has literally been eaten and destroyed by squirrels causing the entire electrical system to be compromised. Safety features have been especially affected including but not limited to air bags, windows being inoperable, door locks being stuck open or closed without a physical key, stabilitrak system arbitrarily shutting off, and windshield wipers working intermittently. Obviously, these are critical systems for the safe operation of this vehicle for the driver, passenger, and members of the public that share the roads. I have had the main harness repaired at a dealership (paid by insurance) but it remains an ongoing safety and financial issue. The dealership identified other portions of the electrical system still need repair and may further compromise safety. Not only were warning lights activated, approximately 10 in-dash messages were displayed warning of malfunction prior to dealership inspection and partial remediation. | Crash: No Fire: No | Unknown |
| May 2025 | POWER TRAIN,AIR BAGS,UNKNOWN OR OTHER | The transmission would purge forward when shifting gears. The shifting was very rough. This vehicle had recently been in accident. | Crash: Yes Fire: No Injuries: 1 Towed Medical attention | Unknown |
| May 2025 | STEERING,ELECTRICAL SYSTEM,ENGINE | 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. | Crash: No Fire: No | Unknown |
| May 2025 | ENGINE | 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. | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN,UNKNOWN OR OTHER,ENGINE | 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 | Crash: No Fire: No | Unknown |
| Apr 2025 | POWER TRAIN | 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 | Crash: No Fire: No | Unknown |
| Apr 2025 | STEERING,ELECTRICAL SYSTEM,FORWARD COLLISION AVOIDANCE | 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. | Crash: No Fire: No | Unknown |
| Mar 2025 | ENGINE | 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. | Crash: No Fire: No | 17,000 |
| Mar 2025 | POWER TRAIN | 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. | Crash: No Fire: No | 94,600 |
| Mar 2025 | ENGINE | Lifters failed and damaged engine at 68000 miles | Crash: No Fire: No | Unknown |
| Mar 2025 | POWER TRAIN | 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. | Crash: No Fire: No | Unknown |
| Feb 2025 | ENGINE | 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) | Crash: No Fire: No | Unknown |
| Feb 2025 | POWER TRAIN,ELECTRICAL SYSTEM | 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. | Crash: No Fire: No | Unknown |
| Feb 2025 | POWER TRAIN | Transmission malfunctioned while driving, causing no available power to move the vehicle. Had to coast in neutral and stopped in the road. Towed the truck to the dealer and they confirmed the transmission has failed. No warning lamps present or pre-indication of failure. | Crash: No Fire: No | Unknown |
| Feb 2025 | ELECTRICAL SYSTEM,UNKNOWN OR OTHER,FUEL/PROPULSION SYSTEM | 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. | Crash: No Fire: Yes | Unknown |
| Feb 2025 | ENGINE | I have a 2018 GMC Sierra 1500 with a 6.2 motor. Back in December of 2024, I had to replace a tie rod, cam shaft, and the lifters. $8400 to get everything replaced. Since my warranty had expired, I had to pay all of this out of pocket. I know there is currently an investigation going on in GMC's 6.2 motors. Almost 900,000 engine failures. This is unacceptable. GMC just needs to man up and send out the recall notice. Since I have already had to pay for my replacements, GMC should do the right thing and and cut me a check. | Crash: No Fire: No | Unknown |
| Feb 2025 | SERVICE BRAKES | I noticed there was an issue regarding the break assist system in my vehicle a few months ago when I went to go for a drive. It is available to be inspected. The issue regarding safety revolves around the difficulty to break. The low amount of brake availability is dangerous in the case of a situation that if I needed to break quickly it is extremely difficult to. I have not had a certified individual confirm the issue at this time. It has not been inspected. The warning message "Break Assist" comes up every time I try to utilize the brakes. I know there are previous recalls, although when I have tried to see if my truck falls under those recalls it does not. | Crash: No Fire: No | Unknown |
| Feb 2025 | POWER TRAIN | Vehicle jumps when shifting gears. When coming to a stop it jumps Forward. Hard shifting. | Crash: No Fire: No | Unknown |
| Feb 2025 | POWER TRAIN | Knocking, stalling, shaking, lost of power and steering problems. Serviced transmission twice and I was advised to serve every 30000 miles!!! I owned several types of vehicles but I never heard such things before. Technician told me that apparently many GMC customers reported same problems. | Crash: No Fire: No | Unknown |
| Feb 2025 | ENGINE | Lifters and cams fatal failure, requiring extremely pricy replacement of the parts affected or replacement of the entire engine! | Crash: No Fire: No | Unknown |
| Jan 2025 | ENGINE | My 2018 Silverado 1500 has had 3 cylinder 4 misfires over a 9 month period that had to be repaired after warranty. This caused the repair/replacement of the lifters. I have had this happen for a forth time this year January 7 2025 with the same code of "cylinder 4 misfire". That means four of the same issues in one year. I can be driving along smoothly, then suddenly from one light to the next, the check engine light comes on with the misfire to cylinder 4 coming on. It was shared with me the AFM can cause this to happen. On the third time of misfire, I saw a little smoke, then once it was repaired with lifters replaced, no smoke and back to running smoothly. This time the intake cam lobe was scored which voided the warranty. I am now at a crossroad as to what to do now, and have parked the truck for now. It is my understanding the 5.3L engine was considered a solid engine until the AFM was installed. Did I mention this is the first "truck" I have ever owned? I have had a Chevrolet vehicle since I was able to drive, and have never had engine problems of this magnitude. My concern now is that this could cause my engine to lock up while I'm driving around and cause a possible accident. I depend on this truck as my mode of transportation, but now I have to make a decision that impacts me greatly as a senior citizen on a fixed income. | Crash: No Fire: No | Unknown |
| Jan 2025 | ENGINE | The failure was a lifter collapsed in my vehicle's motor. I had reduced power and major shuttering due to the issue. If I had been towing a load I would have possibly become a hazard by not maintaining a speed that would have been able to keep up with traffic flow. Also if I had been in an congested traffic area I would have been slower to clear or have major breakdown causing increased backups. It was confirmed by a local shop. There were no warning lights at the time of incident, nor leading up to this incident. Fortunately no accidents or disruptions happened and I had to be towed in to a repair shop. | Crash: No Fire: No | Unknown |
| Jan 2025 | VISIBILITY | The contact owns a 2018 GMC Sierra 1500. The contact stated while driving approximately 35 MPH with the rear window defroster activated, there was a burning rubber odor inside the cabin of the vehicle and there was smoke coming from the rear window area. While inspecting the rear window the contact discovered that the rear window connector cover had melted, and the wire connections were a burning amber color, but no flames were present. After disconnecting the electrical connections, approximately 30 seconds later the rear glass panel on the passenger side suddenly shattered. No injuries were reported. The contact’s young daughter was seated in the rear during the failure. The vehicle was taken to the local dealer, but the cause of the failure was not yet determined. The manufacturer was not notified of the failure. The failure mileage was 60,952. | Crash: No Fire: No | 60,952 |
| Jan 2025 | ELECTRICAL SYSTEM,ENGINE | The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving on the highway at various speeds, the vehicle occasionally shuts off. The contact stated that several unknown warning lights were illuminated. The contact stated that the vehicle was pulled over to the side of the road and restarted. The contact was able to continue driving. The vehicle was taken to a local dealer and was diagnosed; however, the cause of the failure was not found. The contact was informed to take the vehicle back to the dealer if the failure returned. The manufacturer was notified of the failure. The approximate failure mileage was 128,000. | Crash: No Fire: No | 128,000 |