GMC Sierra Complaints (2018)

371 consumer complaints on file.

#11728308March 31, 2026
UNKNOWN OR OTHER
I’ve owner the vehicle since new. My A/C condenser has failed 3 times, meaning I’m now about to be on my 4th. The welds are weak and it cracks in the same spot 95% of the time. It should last more than a 2 year average.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11724945March 17, 2026
UNKNOWN OR OTHER
Premature frame rot
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11723657March 11, 2026
ENGINE, STRUCTURE
The contact owns a 2018 GMC Sierra 1500 Denali. The contact stated that while driving at an undisclosed speed, and while the vehicle was parked, the running boards unexpectedly lowered. Additionally, there was oil leaking from the vehicle, and the check engine warning light was illuminated. The vehicle was taken to the dealer, where it was diagnosed with camshaft failure. The contact was informed that the camshaft needed to be replaced. The vehicle was repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 107,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11722171March 5, 2026
AIR BAGS
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving approximately 45 MPH on bumpy terrain, the driver’s and passenger’s side curtain air bags deployed unexpectedly. No warning light was illuminated, and there was no impact to the vehicle to cause the air bags to deploy. The vehicle was taken to a local independent mechanic, where it remained for further investigation. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 80,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11721830March 3, 2026
ELECTRICAL SYSTEM, STEERING, SUSPENSION
1. Electronic power steering modular issue. My 2018 GMC SEIRRA 1500 CREW CAB JUST LOST ALL POWER STEERING. THEN WHEN I PARK IT. Assist notifications come on, ABS notices, BRAKE light stays on, trailer/tow notifications, trailer assist, parking brake, etc SUDDENLY A LOUD thump & feels like the whole truck just drops like 5” inches, settling. I cannot afford an inspection (ID theft in 2025, compromised all accts & all credit cards) BUT. It IS available as long as cost is covered by YOU !! 2. Lucky it happened in a grocery store parking lot. However not expecting power steering to go out, almost hit a pedestrian. 3. No it has not Ben inspected yet I can’t afford the bill 4. No it has not been reported what for I didn’t hit anybody and the cops in this area they could give her rats ass they don’t make a report the question you like you’re like a criminal. 5. No warnings or anything until it happened that day leaving the grocery store. There is absolutely no notification it was gonna happen. It ran fine when I parked it to grocery shop Come back out & I could barely back out to leave. I can lift up my had fatboy if needed so I’m sure turning a steering wheel…. lol Thnx a lot If I could figure out what part needs to be changed out or you could cover the parts needed. I do work in cars or have in the past, I don’t like the new ones, but this seems simple enough if I knew exactly what part I needed to pull out change out or I see that there’s recalls on previous vehicles and GMC after2020- 24 but I don’t see 2018 didn’t happen so I like to say whoever created that electronic steering can take that module along with the harness and they know exactly where they can put it don’t they I’m just saying as a used to be not sure now a GMC supporter, but I’m starting to think twice now if I
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11721211February 28, 2026
POWER TRAIN
I’ve gone through two transmissions on my 2018 gmc sierra 1500 both times the same issue. The gears are shot, hard shifting. Vehicle is well maintained. Both transmissions one original equipment and second bought at the dealership the truck was bought both only lasted over 80000 miles. Driving the truck loss of power or torque is noticed, then a hard shifting. Checked fluid all was good not seeing metallic shavings. Then the overheating of the transmission, faulty valve replaced with aftermarket bypass and did transmission flush. But each occasion there was an incident I would’ve driving on the interstate and vehicle would lose power and almost hard stop and cause a crash. Then vehicle would only go in reverse both times the transmission gave out. The only warning light that ever came on was a transmission overheating and nothing else. I’m currently in the process of having to get another transmission because of the same issue again. Vehicle was seen by a technician and deemed the transmission was shot again.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11719391February 20, 2026
POWER TRAIN
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle jerked abnormally hard. No warning lights were illuminated. The vehicle was taken to the dealer, where it was diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was repaired; however, the failure reoccurred. The vehicle was taken to the dealer, where it was diagnosed and determined that the transmission was failing. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The contact was informed that the repair was not covered under warranty. The transmission was replaced two years ago. In addition, the contact stated that the original transmission had failed at 130,000 miles. The manufacturer was not made aware of the failure. The failure mileage of the second transmission was approximately 40,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11718452February 17, 2026
POWER TRAIN
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at various speeds, there was an abnormal vibration in the steering wheel. There was no warning light illuminated. The contact stated that the tires were replaced, and the wheels and bearings were inspected by an independent mechanic, but no failure was found. The independent mechanic related the failure to an undisclosed transmission recall; however, the dealer informed the contact that the VIN was not under recall. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was approximately 28,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11714207January 29, 2026
ENGINE, ENGINE AND ENGINE COOLING
The contact owns a 2018 GMC Sierra 1500. While starting the vehicle, it was shaking violently, with reduced power. The vehicle was restarted and worked as designed. Upon research, the contact associated the failure with NHTSA Action Number: PE25001 (Engine and Engine and Cooling). The vehicle was taken to an independent mechanic who determined there was metal in the engine, and there was a misfire coming from cylinder #2. The mechanic recommended that the engine be replaced. There were loose wires from the ECM, and the failure halted after the mechanic secured the wires. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The approximate failure mileage was 150,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11712288January 20, 2026
POWER TRAIN, ENGINE
I OWN A 2018 GMC SIERRA DENALI ULTIMATE, The truck has the 6.2 engine which had the lifter issue as stated with the current situation. At the time, the truck had 37,000 miles when the issues started. I purchased the truck from Andy Mohr with 8806 miles on it in November of 2019. I worked overseas for the DOD so that’s why the miles are low. After I got it fixed, ($4500 dollars at Hare Chevrolet) I experienced the transmission shake while driving home from work with my children in it. The transmission was shaking so bad the whole cab was rocking.That repair was $3,300. Now, the truck has piston slap and rod issues and currently at Hare Chevrolet for service. I was told I need a full rebuild ($12,000 dollars or a new engine $14000 dollars). As a retired Air Force veteran, I didn’t expect issues like this, especially when I baby the truck and it currently has 40,530 miles. I had regular oil changes and service, yet now stuck with a high class truck that has serious issues that seem to be ignored by GM and Andy Mohr GMC. Andy Mohr sold me an extended warranty at time of purchase but I paid for a year and a half that wasn’t usable. If I had that warranty I would be covered now.But besides that, it’s a Denali, I shouldn’t be having a new engine at 40,530 miles. I am happy that there is an investigation but it needs to be widened because my truck was right before the new model rollout but I am having the same issues. If needed, I have all my receipts and information and will provide the service rep at Hare. The reason why its at Hare vs Andy Mohr is due to me catching them not fully servicing my truck and joy riding my Camaro ZL1 after an oil change before I went home for a funeral.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11711924January 19, 2026
ENGINE
The lifters in my engine collapsed. This caused a push rod to be bent and the cam shaft to be damaged causing thousands to fix. While I was driving. I could feel the engine malfunction causing my speed to significantly decrease. The vehicle was fixed through an independent mechanic. Mechanic stated that the active fuel management system is the cause for the lifter collapse. There was no warning before the failure
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11711245January 15, 2026
POWER TRAIN
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle was shaking abnormally. No warning light was illuminated. The vehicle was taken to the dealer to be diagnosed, and it was determined that the engine needed to be replaced. The vehicle was then taken to an independent mechanic, who determined that the torque converter had failed. The torque converter was replaced, but the failure persisted. The vehicle was taken back to the independent mechanic, who replaced the torque converter a second time. The manufacturer was not made aware of the failure. The failure mileage was approximately 140,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11709032January 6, 2026
ENGINE
Engine failure. 6.2l with AFM system Extreme oil consumption Heavy metal in oil Loud ticking 120789 miles Purchase date 05/29/2025 Madras, Oregon Chevrolet Dealer
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11705563December 17, 2025
VISIBILITY:DEFROSTER/DEFOGGER/HVAC SYSTEM:CONDENSOR/EVAPORATOR
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the air conditioning system became inoperable. There was no warning light illuminated. The contact stated that the air conditioning system failed to function properly. The vehicle was taken to an independent mechanic, where it was diagnosed, and determined that the air conditioning condenser had failed and needed to be replaced. The vehicle was not repaired. The dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was not available.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11705328December 16, 2025
SERVICE BRAKES, ELECTRICAL SYSTEM, FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING
Driving on the freeway going approx 70 MPH and the ABS warning light, and Stabilitrak warning light suddenly turned on. I’m sure you can imagine how panicked I was going that fast on the freeway and having my brake warnings suddenly turn on. Especially with my entire family in the vehicle with me at the time. Could feel a difference when I was attempting to brake and exit the freeway. Had to apply tons of pressure to get the brake pedal to engage. The cruise control would no longer work, and the trailer brake monitoring system also began flashing. Truck has been to 2 GMC dealerships the ABS module was replaced made it approximately 2 miles and it came back on. Truck is currently waiting for another part to attempt to fix the problem. Truck has 86,000 miles on it.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11705013December 15, 2025
ENGINE, POWER TRAIN
I have 125,000 miles on my truck. I was traveling with my grandkids in the back seat. We were going through a four way stop. My truck started tapping like a lifter issue. The next thing I know is the truck engine light started flashing and car started to shake. Then, my truck lost all power and a big cloud of blue smoke came out of the tail pipe. The truck could not be driven any further. The symptoms: engine tapping, low oil, engine light flashing, shaking, lost all movement, and a cloud of smoke We had to tow my truck to the dealer and they are still accessing the issue. All symptoms are identical to the current recall of the GMC engines.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11700630November 20, 2025
ENGINE
The injector failure in my 2018 GMC Sierra 1500 resulted in repeated misfire conditions (P0300 and P0307), causing the vehicle to lose power unexpectedly while driving. The engine would hesitate, shake, and struggle to accelerate, especially during merging or highway speeds. These symptoms created a significant safety hazard because the vehicle could not reliably maintain speed or respond to throttle input. Sudden power loss in traffic exposes the driver and surrounding motorists to an increased risk of collision, particularly during lane changes, freeway merging, intersection crossings, and passing maneuvers. The dealership confirmed internal injector failure, and the vehicle has been out of service for three months without resolution. This is a safety-critical defect that compromises vehicle controllability, stability, and safe operation on public roads.”
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11700188November 18, 2025
POWER TRAIN, ENGINE
2018 GMC Sierra started having shuddering/jerking/jumping problems at around 60k miles. This problem occurs while driving on straight aways, going uphill and while in drive at a stop sign/light. When the gas is accelerated the truck then hesitates and jerks/jumps. We have taken it to the GMC dealership and paid for the diagnostics and were informed “the problem wasn’t severe enough”. The truck has only been serviced by GMC dealership. So after failed attempts with GMC service department we have taken it to a local small auto shop and they automatically said it was the Drive Train and needed to be taken to a transmission shop. We have been GM owners for decades and are so disappointed in the service received from them.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11699411November 14, 2025
POWER TRAIN:AUTOMATIC TRANSMISSION:TORQUE CONVERTER
The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the transmission vibrated. No warning lights were illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed with a failing torque converter. The contact was informed that the torque converter needed to be replaced. The vehicle was not repaired. In addition, the contact was informed of a Manufacturer's warranty. The contact was informed of a Manufacturer's warranty for the 2018 GMC vehicle's transmission failure due to the incorrect oil being used during production of the torque converter. The dealer was made aware of the failure; however, the contact was informed that the manufacturer needed to approve the repair coverage. The manufacturer was made aware of the failure but provided no assistance. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 89,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11698051November 7, 2025
POWER TRAIN
Repeated transmission issues with the 8 speed transmission due to the malfunctioning valve body. This has caused major safety issues and nearly killed my family with the vehicle locked up and wouldn’t shift on the interstate. The dealership did a warranty repair on the torque converter which made the symptoms slightly better until the vehicle was no longer covered by warranty, at which time all symptoms came back. GM knows their 8 speed transmission has an issue and hasn’t provided a solution. Now, due to the faulty valve body, I have to have my entire transmission replaced for $8000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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