After cold starts when accelerating the transmission slips from 1st to 2nd and throws your body forward. After that first gear change it doesn't do it again until another cold start. Around 34000 miles I am getting a rumbling vibration through the dash and steering wheel when holding speed between 35-75 MPH. The RPM guage will jump slightly and it will feel like going over rumble strips.…
2018 GMC Sierra powertrain problems
severe 115 complaints filed with NHTSA · avg repair $2,500 · see powertrain across all vehicles →
Failure mileage
Complaints
115
Recalls
0
Avg fix
$2,500
4crashes
3injuries
When does it fail?
Of the 115 powertrain complaints filed for the 2018 GMC Sierra, here's the actual mileage breakdown — failures cluster heaviest at 25,000-50,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Powertrain accounts for 39% of every owner complaint on file for this vehicle — the dominant problem area across 12 categories tracked.
Owners have filed 115 powertrain complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
The failure pattern owners describe
The 2018 GMC Sierra has widespread transmission and engine issues that GM is aware of but has not recalled. Transmission problems dominate complaints: hard 1–2 shifts (especially on cold start), shuddering, loss of power, and limp-mode failures occur from 5,700 miles onward. Multiple owners report the 8-speed transmission shuddering at 145°F–192°F, hesitating or refusing to shift, and forcing full replacement at $6,000–$8,000. GM Service Bulletins acknowledge the issue but state no fix exists and that replacing the transmission won't solve it. Some owners report a second transmission failure within 40,000–80,000 miles of the first replacement.
Engine lifter failures in the 6.2L V8 cause ticking noises (sometimes audible from day one), loss of power, rod knock, and engine shutdown while driving. Repairs run $4,500–$14,000 for lifter replacement, rebuild, or full engine replacement—all on vehicles with low mileage and regular service. Owners report the dealership initially dismisses ticking as "normal." Additional failures include torque converter replacement (sometimes twice), brake system failures with smoke and unexpected locking, and excessive idle vibration unresolved after multiple dealer visits.
Many owners explicitly mention class-action lawsuits and state that GM knew of these defects before sale but did not disclose them. Warranty denials and manufacturer runarounds are standard. No recall had been issued for the transmission as of these complaint dates, despite clear pattern and safety risk.
Same GMC Sierra powertrain reports on nearby years: 2015 · 2016 · 2017 · 2019 · 2020
Failure modes owners describe
Hard shifting and transmission jerking between gears
Transmission shifts abruptly and harshly, particularly between 1st and 2nd gear, sometimes causing the vehicle to lurch or jerk. Occurs frequently on cold starts and light acceleration. Owners report this as a known defect in the 8-speed transmission.
When: Present from new in many cases; worsens over time. Often occurs on cold starts or first shift of the day. Reported from 5,700 miles to 80,000+ miles.
Symptoms owners cite: Hard 1-2 shift on cold start; Jerking or lurching sensation during acceleration; Transmission hesitates to shift; Loss of power during shift; Vehicle lurches forward unexpectedly
Repairs/costs cited: Transmission fluid flushed and changed; torque converter replaced in some cases; transmission relearn/software update attempted; ultimately requires transmission replacement ($6,000–$8,000 cited)
Recalls/TSBs owners mention: GM Service Bulletins (TSB #16-NA-361, #18-NA-355) acknowledge the issue but state no resolution exists. Some TSBs note that replacing the transmission will not solve the problem. Dealers claim it is 'normal' behavior or await technical bulletins. Class action lawsuit filed by owners.
Transmission shuddering and vibration at various speeds
Vehicle experiences shuddering or vibration through the transmission, especially during highway driving or when torque converter engages. Often linked to incorrect transmission fluid used during production or failing torque converter.
When: Reported from 18,000 miles onward; worsens with time and heat. More pronounced at highway speeds (45–75 mph) or at idle.
Symptoms owners cite: Shuddering or shaking through steering wheel; Vibration from transmission area; Increased vibration as speed increases; Shuddering on upshift; Transmission fluid temperature rises to 145–192°F triggering poor shift quality
Repairs/costs cited: Transmission fluid flushed and replaced; torque converter replaced (some owners report replacement twice without resolving issue). Some cases required full transmission replacement. Diagnostic costs mentioned ($850 cited for flush and diagnosis).
Recalls/TSBs owners mention: Manufacturer warranty exists for incorrect oil used in torque converter production. GM Technical Service Bulletins issued but repairs denied or require manufacturer approval. Special Coverage Adjustment program referenced (N182188930). Dealers often state shuddering is 'normal' or within specifications.
Transmission failure and loss of drive power
Transmission fails to shift properly, vehicle loses power, or refuses to move forward despite engine running. Includes instances where vehicle enters limp mode (locked in 1st gear) or fails to accelerate beyond low speeds.
When: Occurs without warning; reported from 13,000 to 131,000 miles. Multiple owners report failures within first year of ownership.
Symptoms owners cite: Vehicle locked in first gear (limp mode); Transmission won't shift up or down; Loss of forward motion despite accelerator input; RPMs surge to 3,000–5,000+ but vehicle does not accelerate; Vehicle rolls backward when in Drive
Repairs/costs cited: Full transmission replacement required ($6,000–$8,000 range); some second transmissions failed within 40,000–80,000 miles; valve body replacement attempted in some cases ($3,300 cited); full transmission rebuild or replacement cited as only solution.
Recalls/TSBs owners mention: No recalls issued at time of complaints. Warranty denials reported. Endurance warranty denied coverage. GM referred consumers to NHTSA Hotline. Class action lawsuit mentioned by owners.
Engine lifter failure and active fuel management malfunction
Valve lifters in cylinders fail, causing ticking/tapping noise, loss of power, cylinder damage, and potential piston/rod failure. Occurs in 6.2L V8 engines equipped with active fuel management system (cylinder deactivation).
When: Reported as early as first day of ownership (ticking noted immediately); failures also occur at 36,000–40,500 miles despite low mileage and regular service.
Symptoms owners cite: Ticking or tapping noise from engine; Loss of engine power while driving; Check engine light (sometimes flashing); Engine shaking or vibration; Blue or white smoke from exhaust; Engine cuts out or stalls while in motion; Knocking or rod knock sound; Misfire condition
Repairs/costs cited: Lifters replaced; in severe cases engine rebuild required ($12,000 cited) or full engine replacement ($14,000 cited). One owner paid $4,500 for lifter repair, then $3,300 for transmission repair. Multiple costly repairs required even at low mileage.
Recalls/TSBs owners mention: GM acknowledged similar issue on 6.3L V8 engines with active fuel management but not yet extended to all 6.2L models at time of complaints. Some owners mention existing recall on 6.3L but vehicle year not included. No TSB or recall cited by dealers for 2018 6.2L in these narratives.
Transmission overheating and thermal shutdown
Transmission overheats, causing loss of shift capability and vehicle immobilization. Owners report transmission temperature rising to 154–192°F, triggering failure to shift and forcing limp mode.
When: Reported at 11,000–25,000 miles; occurs during normal driving and highway operation.
Symptoms owners cite: Transmission temperature gauge reads 154–192°F (normal is ~140°F); Transmission stops shifting properly at elevated temperature; Vehicle enters limp mode or safe mode; Engine RPMs spike without acceleration; Loss of transmission fluid pressure
Repairs/costs cited: Transmission cooler line failure diagnosed in one case, damaging transmission. Auxiliary transmission oil cooler line rupture cited. Transmission fluid flushed and replaced; ultimately transmission replacement needed.
Recalls/TSBs owners mention: No manufacturer response documented in these complaints. Dealers unable to provide immediate repair due to parts backlog and production strikes. One dealer stated vehicle unsafe to drive pending teardown diagnosis.
Torque converter failure and repeated replacement
Torque converter fails prematurely, causing shuddering, slipping, and loss of drive. Some owners report torque converter replaced twice with same symptoms recurring.
When: Reported from 22,000 miles onward; second failures occurring 40,000+ miles after first replacement.
Symptoms owners cite: Shuddering or vibration while driving; Transmission slipping (engine revs but vehicle doesn't accelerate); Torque converter shuddering, especially on upshift; Transmission overheating due to converter wear
Repairs/costs cited: Torque converter replaced (cost not always cited); some replaced twice without resolving issue. Incorrect transmission fluid cited as cause in TSB notes; fluid change alone does not resolve problem for many owners.
Recalls/TSBs owners mention: Warranty program exists for incorrect oil used in torque converter production. Manufacturer warranty covers partial cost, owner responsible for balance. Some dealers refused to replace until TSB issued.
Starter failures and repeated replacement
Starter motor fails repeatedly, leaving vehicle unable to start without jump-start. Owner reported being on third starter.
When: Reported as recurring issue over ownership period.
Symptoms owners cite: Weak starter engagement (slow cranking); No start condition requiring jump-start; Intermittent starting failure
Repairs/costs cited: Starter replacement; third replacement reported by owner.
Transmission grinding and noise
Grinding or unusual noises emanate from transmission area during acceleration or shifting.
When: Reported at 80,000 miles and ongoing.
Symptoms owners cite: Grinding sound when accelerating; Abnormally loud sound from underneath vehicle near transmission
Repairs/costs cited: Diagnostic testing performed; no failure found in some cases.
Brake system failure and unexpected locking
Brakes slip, lock up unexpectedly, or fail to respond. In one case, smoke came from brake pedal area and brakes locked at highway speed.
When: Reported at 55 mph during deceleration; brake system degradation over time.
Symptoms owners cite: Brake pedal smoke; Brakes lock up unexpectedly; Loss of braking response; Brakes slip and fail to hold vehicle
Repairs/costs cited: Brake system replaced; failure persisted in at least one case.
Vehicle idle vibration and driveline vibration
Vehicle vibrates excessively at idle and at highway speeds (60+ mph). Multiple dealer visits found no issue; tires replaced without resolution.
When: Reported since day one of ownership in some cases; 7+ months of unresolved complaints.
Symptoms owners cite: Vibration at idle; Vibration at highway speeds (60–75 mph); Steering wheel shaking; Distraction and concern while driving
Repairs/costs cited: Tires balanced three times; tires replaced; dealer found no issue and claims vibration meets specifications.
Recalls/TSBs owners mention: Dealers claim vibration is 'normal' and meets GM specifications. No resolution offered after 7 months and 5 dealer visits.
Front axle/suspension failure
Front wheel detached from vehicle while driving, causing loss of steering control and vehicle to skid.
When: Reported at 14 months of ownership; vehicle was recently serviced with no issues flagged.
Symptoms owners cite: Front right wheel detached while driving; Sudden loss of control; Vehicle skidded to right; Major suspension and other damage
Repairs/costs cited: Not repaired (owner pursuing legal action)
Synthesized from 115 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 6 most recent
The contact owns a 2018 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the engine temperature rose to 210 degrees and the vehicle started jerking. The contact stated that the failure also occurred while idling for a while, or while stopped at a traffic light while refueling, and before accelerating. The failure occurred once the engine temperature rose to 210 degrees.…
I own a GMC sierra which is 14 months old, purchased in dubai uae from alghandi auto. The last service for 40000 kms was done on august 8th, 2019 and no problem was highlighted except the battery that was subsequently changed. On friday early morning (sep 27, 2019), we have escaped a major accident on sheikh zayed road on account of the front wheel axle that just broke/came apart while driving,…
The contact owns a 2018 GMC Sierra 1500. The contact stated while driving 50 MPH, the vehicle started shaking and vibrating abnormally. There was no warning light illuminated. The vehicle was taken to the dealer to be diagnosed. The contact was informed that the transmission oil needed to be flushed. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was 71,000.
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…
During down shifting in lower gears while reducing speed , transmission makes a loud noise followed by vehicle hard lounging forward . Occurance is intermittent and unpredictable . In city traffic this has potential to cause an accident because vehicle lounges forward when speed is reduced . Vehicle has 18900 miles . Made in 2017 .
Had powertrain trouble with your 2018 GMC Sierra?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the powertrain problem on the 2018 GMC Sierra?
It's a meaningful issue. 115 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $2,500.
At what mileage does the powertrain typically fail?
Across the 48 complaints that reported odometer mileage, most powertrain failures cluster between 15,000 and 81,000 miles, with the median around 32,000. A quarter of owners report trouble before 15,000; a quarter make it past 81,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to powertrain?
No active recalls currently cover powertrain issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2018/GMC/Sierra.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.