GMC Sierra Complaints (2018)

371 consumer complaints on file.

#11770114October 9, 2026
POWER TRAIN
My 2018 GMC Sierra 1500 experienced significant transmission problems that began as rough, inconsistent shifting, hesitation, and abnormal transmission behavior before eventually progressing to complete transmission failure. These symptoms were present before the transmission's ultimate failure and while the vehicle was still within its warranty period. Unfortunately, during the COVID-19 pandemic, local dealership service departments faced significant staffing shortages and appointment backlogs, making timely diagnosis and repair extremely difficult. By the time the transmission failed completely, the vehicle had exceeded the warranty's 84-month time limitation but remained substantially below its mileage limitation. Despite the relatively low mileage, the earlier symptoms, and the extraordinary circumstances affecting service availability, General Motors declined to provide warranty or goodwill assistance. I was forced to bear the substantial financial burden of a major transmission failure in a vehicle that had not reached the mileage threshold established under its warranty. I believe this failure warrants investigation because transmission problems involving GM trucks and SUVs from this period have been widely reported by other owners. I am particularly concerned about whether GM was aware of recurring transmission defects, whether affected owners received adequate notification, and whether these failures present a potential safety risk through unexpected loss of propulsion, hesitation, or unpredictable shifting. I request that NHTSA review this complaint alongside similar reports involving 2018 GMC Sierra transmissions to determine whether a recurring defect exists and whether further investigation or corrective action is warranted.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11765772September 21, 2026
ENGINE
I was backing out of my garage and truck made strange noise and shut off . Tried to restart but just made ding and wouldn't turn over . Dash lights went blank. Had vehicle towed to shop and mechanic stated it was crank and connecting rods after he dropped the oil pan. I ordered new OEM engine and waiting on delivery . Been 5 weeks now since order . Vehicle only has 106,000 miles on it and have had it since 20,000 miles and all maintenance has always been done . Engine can be inspected at shop as new engine has not arrived
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11765804September 21, 2026
ENGINE
CUSTOMER STATES: THINKS CRANKSHAFT PULLEY IS LOOSE DUE TO PRIOR WATER PUMP REPLACEMENT-CRACKSHAFT PULLEY HAS NOTHING TO DO WITH WATER PUMP REPLACEMENT. BEFORE INSPECTING/STARTING ENGINE VERIFIED OIL LEVEL-OIL LEVEL IS ON FULL MARK. STARTED ENGINE-LOUD RATTLING/KNOCKING NOISE FROM ENGINE-ENGINE HAS INTERNAL FAILURE-ENGINE REPLACEMENT IS REQUIRED. ALSO HEARING NOISE IN REAREND-CANNOT TEST DRIVE DUE TO ENGINE CONDITION SEVERAL TSB'S ON ENGINE FAILURES WITH 6.2L ENGINES. GM HAS POSSIBLE RECALLS COMING ON 2019-2024 YR MODELS. NOT SURE IF EARLIER MODELS MAYBE INCLUDED UNDERHOOD INSPECTION 1 7003186 06NS 52.50 52.50 LBR-DISC CUST SAT
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11765024September 17, 2026
POWER TRAIN
Vehicle purchased Certified Pre-Owned in October of 2021 with roughly 43,000 miles. During the first service (47,598 miles) at a GM dealer I reported very hard shifts, but this issue was ignored during service. At the next servce (54,571 miles) I again reported the hard shifts and "surging" when coming to a stop but the dealer reported they were unable to replicate the issue and did not address it. At the next service (61,620 miles) I reported the issues with the transmission once again and this time they performed a transmission fluid flush/replacement, acknowledging the issue and asking me to drive for 200 miles and return if the issue was not fixed. I returned at 62,058 miles as the issue was not resolved and they replaced the torque converter. During my next visit (68,709 miles) I reported the issue was still present but was informed they would not address it as I was now outside of warranty. I reported this to GM but was told to pay for a diagnostic and repair and "hope" that the dealer would elect to cover it.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11764851September 16, 2026
POWER TRAIN, SUSPENSION
Unknown
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11762401September 6, 2026
POWER TRAIN, ENGINE
I own a 2018 GMC Sierra 1500 V8 5.3 liter which is at 46, 433 miles. Over the past few weeks I have noticed the transmission having difficulty shifting in first gear and lurching, and making shuddering noises, and as well making a constant ticking noise. After an experienced mechanic had put a diagnostic system onto my truck, his system diagnosed a Transmission Lifter Failure, specifically 2 out of the 8 lifters. A few days later (9-04-26) I took my truck to a certified GMC servicing business (Patriot Chevrolet of Hopkinsville KY 270-886-1207) and had a transmission servicing done. I had told the Customer Service representative Amanda Williams about the ticking and that I thought 2 lifters going bad in the transmission were the source of it. 3 hours later the servicing was done which cost $ 474.43. She did not know if the ticking had stopped or not. I started my engine to head home and the ticking was still happening. Nothing had changed. I got home, parked and have not started the engine since to minimize any further damage. I have become aware that this year, make and model has become infamous for the engine/transmission design and parts failure which has been at the center of thousands of class action lawsuits. I have owned this vehicle since inheriting it from my late father for 2 months before he developed dementia and suffered a broken hip. I have religiously had the oil changed every three months regardless of the mileage, and this is a sealed transmission which cannot be worked on by someone but a certified GMC mechanic, which wasn't a worry because the truck's manual says doesn't need to be worked on unless there seem to be problems. Which is what I did on 9-4-26, hoping that a servicing would fix the issue. During the 5 years that I have owned this truck, I never received ANY sort of notice from GMC that might've hinted at possible Transmission Failures, though GMC has been totally aware of. Sudden power loss dangerous and unfairly expensive to drivers.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11762122September 4, 2026
POWER TRAIN
Within the first 3 years of purchase as a new vehicle, my 2018 GMC Sierra Denali equipped with the GM 8L90 automatic transmission developed a pronounced judder during light acceleration, resembling driving over rumble strips. The condition was first reported to an authorized GMC dealer on October 23, 2021, at 26,648 miles while the powertrain warranty was in effect. GM authorized a transmission-fluid exchange from the technical service bulletin (TSB) 18-NA-355, dated April 2020, but that repair did not provide a lasting correction. The condition continued, and in 2026 the authorized dealer diagnosed an “internal stator issue causing judder on light acceleration” and recommended replacement of the torque converter. We completed the repair and retained the removed converter. The defect affected the vehicle while accelerating and created concern about predictable power delivery when merging, entering traffic or crossing an intersection. Continued torque-converter malfunction can generate heat and debris, damage the transmission and potentially impair acceleration or power transfer. GM had issued technical bulletins addressing torque-converter shudder in 2018 Sierra vehicles before this truck was purchased, but there has been no recall. I request that NHTSA evaluate whether this recurring defect presents an unreasonable safety risk in GM vehicles equipped with the 8L90 transmission.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11761343September 1, 2026
POWER TRAIN
Automatic Transmission not shifting properly unable to accelerate bangs gears while shifting noises from the transmission not reported no warning lamps
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11759679August 26, 2026
SERVICE BRAKES, ELECTRICAL SYSTEM
There was a mass recall on 2018 GMC Sierras to due to a faulty break pump vaccum. We are experiencing the same problems but for some reason were not included in the recall. We were told to reach out on here as others have to see what can be done as this is a saftety hazard.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11756121August 11, 2026
STEERING, ENGINE
Head gasket failure and overheating. After fixed, power steering has just failed during driving. Will have to have it towed to shop
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11755159August 6, 2026
SEAT BELTS
THE FRONT PASSENGER SIDE SEAT BELT RETRACTOR IS FAILING TO RETRACT. I HAD A PASSENGER IN THE VEHICLE AND AS WE CAME TO A STOP IN MY DRIVEWAY TO EXIT THE VEHICLE SHE UNHOOKED (RELEASED) THE SEATBELT AND IT WILL NOT RETRACT. THE SEATBELT IS NOW CURRENTLY EXTENDED OUT AND WILL NOT RETRACT BACK INTO THE RETRACTOR. I PURCHASED THE VEHICLE TODAY 08-05-2026, I CALLED THE DEALER I PURCHASED IT FROM AND THEY STATE THAT THERE IS NO RECALL ON THE VEHICLE WITH THIS ISSUE. I DID LOOK THE ISSUE UP ON GOOGLE AND INFACT IS STATES A PROBLEM WITH THE SEATBELT RETRACTOR FOR MY VEHICLE. I SENT THEM A SCREENSHOT OF THE CONFIRMATION FOUND AND THEY DECLINE TO ACKNOWLEDGE A REPAIR STATING THERE IS NO RECALL. I WAS ABLE TO MANUALLY FEED THE BELT BACK INTO THE RETRACTOR, IT WAS EXTREMELY DIFFICULT BUT I SAT IN THE SEAT TO DUPLICATE THE ISSUE AND IT WILL DUPLICATE. THE SEATBELT IS CURRENTLY EXTENDED AND WILL NOT RETRACT AUTOMATICALLY. THE SHOULDER STAP WILL NOT FIT SECURELY AROUND A PASSENGER AT THIS TIME. I HAVE HAD NO PRIOR USE OF THE VEHICLE UNTIL TODAY AS I PURCHASED IT FROM A REPUTABLE DEALER WHO STATES THEY DID A FULL INSPECTION OF IT PRIOR TO SELLING BUT APPARENTLY THIS ISSUE WAS NOT REPAIRED PRIOR TO SELLING IT.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11754023July 31, 2026
ENGINE, FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL
ENGINE FAILURE, 5/3/22, 23,987 MILES, ALL LIFTERS WAS REPLACED UNDER WARRANTY, ENGINE FAILURE, 7/6/26, 46004 MILES, TOOK TRUCK IN FOR OIL CHANGE AND WHEN RETURNED HAD A TICKING NOISE. DEALERSHIP NOTIFIED ME THAT CAMSHAFT ISSUES AND METAL DETECTED IN OIL. ENGINE NEEDS REPLACED. 6.2 V8 2018. TURPIN MOTORS, GENESEO, IL HAS DONE ALL SERIVCE ON TRUCK. NO WARNING LIGHTS OR CODES. VEHICLE IS IN MY GARAGE AND AVAILABLE FOR INSPECTION. I OPENED CASE WITH GM #105652237. DEALERSHIP OPENED CASE ON GM PORTAL ALSO. RESPONSE FROM GM IS THAT TRUCK IS OUT OF WARRANTY
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11743611June 11, 2026
POWER TRAIN, ENGINE
Vehicle Details: 2018 GMC Sierra 1500 Z72 4x4, 5.3L V8 EcoTec3 engine, VIN: [XXX] Mileage at time of incident: 220,000 miles Location: [e.g., Little Rock, Arkansas area or specific road/highway – please provide if desired] What happened: The 5.3L V8 engine’s hydraulic roller lifters failed. One or more lifters collapsed, stuck, or lost proper oil pressure/operation. This led to improper valvetrain function, causing loud ticking/knocking noises, cylinder misfires, significant loss of engine power and performance, and internal engine damage (such as camshaft lobe wear or related components). Component or system that failed or malfunctioned: Hydraulic valve lifters (camshaft followers) in the engine valvetrain, associated with the Active Fuel Management (AFM) system. The failed lifter(s) and related components are available for inspection upon request. How safety was put at risk: The engine malfunction resulted in sudden or progressive power loss and misfiring while driving. This reduced the vehicle’s ability to accelerate or maintain speed, especially in traffic or on highways, creating a hazardous situation that put my safety and the safety of other road users at risk of collision or breakdown. No accident or injuries occurred , or other symptoms prior to the failure with details recall, e.g., ticking noise timeline, misfires Has the problem been reproduced or confirmed by a dealer or independent service center? “Yes, confirmed by shop inspection” Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? [Yes] Additional notes: Repair estimate is approximately $20,000 (likely due to extent of internal damage requiring major engine work or replacement). This failure aligns with a well-documented issue in GM 5.3L engines equipped with AFM. Vehicle status parked INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11743173June 10, 2026
STEERING
Power steering went out for 2-3 seconds as I was making a turn into a street , this happened twice to be exact
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11741547June 2, 2026
ENGINE, SERVICE BRAKES, STEERING
Incident description: On three occasion I have had the same catastrophic Engine failure putting myself and my family along with the general public in harms way. Starting March of 2022 while driving at approximately 60 MPH on the West Shore Expressway my truck experienced a sudden and total loss of motor power. My engine stalled out and I lost my ability to safety steer and stop my vehicle. This all happened during rush hour while driving in the left lane of traffic. This sudden loss of power forced me to maneuver the vehicle to the right shoulder of the expressway across the right lane of traffic. As there was no shoulder to pull over on the left side of the highway. This created an immediate crash risk for myself and other drivers. Upon inspection at the authorized GMC dealership where I purchased the truck new, a certified mechanic determined that the engine experienced a complete failure requiring replacement or rebuilding of the engine. I paid to have the engine rebuilt at the dealership. The second instance was similar to the above incident. Once again I paid for the repair. The third instance was more dangerous as when my trucks engine failed it almost caused an accident. As of today my truck is still sitting in the dealership for over 6 months and no one from the dealership or manufacturer will give me an answer on what has to be done now. This patter of sudden repeated engine failure clearly indicates a systemic safety defect that extends beyond normal wear and tear. I urge the NHTSA to open a defect investigation into the 2018 GMC Sierra 1500 engine systems.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11738475May 18, 2026
STRUCTURE:BODY
Paint flaking top above windshield within one year of ownership! Paint flaking on left rear door within last month!
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11738210May 15, 2026
POWER TRAIN, SUSPENSION
The transmission has always been rough. It has now gone out at 75,000 miles. This transmission issue really seemed to get worse about 50,000 miles. But when I called the dealer, they said they were backed up and couldn't get to it for 9-12 weeks (Covid excuses at that point). Then, it really had an issue going down a large grade into [XXX] . But the issues seemed fairly intermittent. I had an independent shop who said it was hard to tell if it was intermittent. They didn't find metal shavings at the time. ADDITIONALLY, it has also always been a little rough driving. A mechanic looking at it today told me there are no sway bar links at all. This truck has not been modified. This had to have come off the line faulty. Among all the other things. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11736800May 9, 2026
ELECTRICAL SYSTEM, ENGINE, FUEL/PROPULSION SYSTEM
GM Duramax L5P diesel engine electrical connector for #4 fuel injector. This failure caused the Diesel exhaust brake, which controls downhill speed, to disengage, extreme shaking of the vehicle, emissions system warning and speed limiting. This occurred while descending a steep grade while towing a 34 feet long, 10,000 pound trailer. This is a known issue with this diesel engine and documented in GM Technical Service Bulletin 23-NA-027. Inspection and repair at a GM dealership confirmed a known issue with the #4 injector pigtail connector caused by improper wire routing and interference wit the Sound Shield and Valve Cover Heat Shield This was a sudden failure of the #4 pigtail connector with no advance warning. In addition to violent shaking of the vehicle, multiple warnings on the DIC indicating that the Diesel Brake was disengaged, the emission system had an issue, and speed would be limited.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11734912April 30, 2026
FUEL SYSTEM, GASOLINE
The contact owns a 2018 Gmc Sierra 3500. The contact stated while operating the vehicle at an undisclosed speed the vehicle suddenly shutoff, the vehicle was coasted to side of the road. The contact referenced NHTSA Campaign Number: 21V739000 (FUEL SYSTEM, GASOLINE) however, the VIN was not included in the recall repair. The vehicle was towed to a dealer where it was diagnosed to be the fuel control module. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 177,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728807April 2, 2026
POWER TRAIN
The contact owns a 2018 GMC Sierra Denali 1500. The contact stated that on several occasions while driving at speeds over 30 MPH, the vehicle started shaking abnormally. The contact stated that the vehicle stalled while driving on three separate occasions and stalled twice while slowing down. There was no warning light illuminated. The vehicle was able to restart each time, but on one occasion, several attempts were needed to restart the vehicle. The vehicle was taken to a dealer, where it was diagnosed, and determined that the transmission, torque converter, exhaust gaskets, filter, and 8D fluid needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 87,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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