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 2026 | STRUCTURE | Paint flaking top above windshield within one year of ownership! Paint flaking on left rear door within last month! | Crash: No Fire: No | Unknown |
| May 2026 | SUSPENSION,POWER TRAIN | 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 | Unknown |
| Mar 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 | Unknown |
| Mar 2026 | UNKNOWN OR OTHER | Premature frame rot | Crash: No Fire: No | Unknown |
| Mar 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 | 80,000 |
| Mar 2026 | STEERING,SUSPENSION,ELECTRICAL SYSTEM | 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 | Unknown |
| Feb 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 | Unknown |
| Feb 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 Towed | 130,000 |
| Feb 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 | 28,000 |
| Jan 2026 | ENGINE AND ENGINE COOLING,ENGINE | 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 | 150,000 |
| Jan 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 | Unknown |
| Jan 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 | Unknown |
| Jan 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 | 140,000 |
| Jan 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 | Unknown |
| Dec 2025 | VISIBILITY | 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 | Unknown |
| Dec 2025 | POWER TRAIN,ENGINE | 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 | Unknown |
| Nov 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 | Unknown |
| Nov 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 | Unknown |
| Nov 2025 | POWER TRAIN | 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 | 89,000 |
| Nov 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 | Unknown |
| Oct 2025 | POWER TRAIN,SEATS,ENGINE | I purchased a 2018 GMC Sierra 1500 6.2 Denali new. I followed all service requirements including oil changes by GM dealerships. 2025 i noticed my truck power was decreasing. Than I started to hear knocking noses. I took it to a dealership for diagnosis but they couldn't identify anything. Finally it started to skip this is when a dealership diagnose it as being an issue with the active fuel management system. They said my lifters, camshaft, and various other parts was damaged and had to be replaced. Additionally, they said it was a recall on 6.2 engines with the same identical issue but my year wasn't included. The cost to repair approximately 10,000. I really need your attention to this matter! September 10, 2025 my truck placed me and others in danger when it lose engine power. Also my engine light was on for the first time. | Crash: No Fire: No | Unknown |
| Oct 2025 | ENGINE AND ENGINE COOLING | The contact owns a 2018 GMC Sierra 1500. The contact stated that while attempting to accelerate from a stoplight, the vehicle hesitated before accelerating. A day later, the failure reoccurred, and the RPMs increased before the vehicle accelerated. There were no warning lights illuminated. The vehicle was taken to the dealer, who diagnosed that the connecting rod had failed, and there were metal shavings inside the engine. The contact was informed that the engine needed to be replaced. The contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); however, the VIN was not included. The vehicle was not repaired. The manufacturer was informed of the failure and confirmed that there was no recall on the VIN. The manufacturer opened a case for the failure. The manufacturer referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 169,000. | Crash: No Fire: No | 169,000 |
| Oct 2025 | ELECTRICAL SYSTEM | Odometer Fraud. The contact purchased a 2018 GMC Sierra 1500. The contact discovered that there was a mileage discrepancy after the purchase. The vehicle was a private sale. At the time of purchase, the vehicle mileage was 72,000. It was later discovered later that the mileage was 241,556. | Crash: No Fire: No | 241,556 |
| Aug 2025 | POWER TRAIN | Transmission shutters when going over 50mph | Crash: No Fire: No | Unknown |
| Aug 2025 | POWER TRAIN | The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed toward the residence, the accelerator pedal was depressed and traveled to the floorboard, and the vehicle failed to drive forward as intended. The vehicle started rolling backwards and the contact carefully maneuvered the vehicle while attempting to park. There was no warning light illuminated. The vehicle was towed to the dealer and diagnosed with transmission failure. The contact was informed that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 101,000. | Crash: No Fire: No Towed | 101,000 |