This preliminary informational (PI) bulletin provides information to dealership personnel that may be helpful when addressing underbody component corrosion with customers.
full bulletin at NHTSA ↗2018 GMC Acadia powertrain problems
moderate Owners of the 2018 GMC Acadia have filed 155 NHTSA complaints about the powertrain, typically surfacing around 37,000 miles at roughly $2,500 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See powertrain across all vehicles →
Failure mileage
Complaints
155
Recalls
0
Avg fix
$2,500
| Model year | powertrain complaints |
|---|---|
| 2014 Acadia | 32 |
| 2015 Acadia | 19 |
| 2016 Acadia | 20 |
| 2017 Acadia | 227 |
| 2018 Acadia (this page) | 155 |
| 2019 Acadia | 145 |
| 2020 Acadia | 19 |
| 2021 Acadia | 15 |
| 2022 Acadia | 4 |
3crashes
3injuries
When does it fail?
Of the 155 powertrain complaints filed for the 2018 GMC Acadia, 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 40% of every owner complaint on file for this vehicle — the dominant problem area across 8 categories tracked.
Owners have filed 155 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.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This bulletin provides information on identifying Non-GM Engine Calibrations for Gasoline Engines using the Tech 2 or GDS 2.
full bulletin at NHTSA ↗This service bulletin provides information on the harmful effects of ethylene glycol in transmission fluid.
full bulletin at NHTSA ↗This informational bulletin explains Unscheduled Supplemental Services and the importance of GM Simplified Maintenance Schedules.
full bulletin at NHTSA ↗This service bulletin informs the technician of an alternate lift procedure that has been developed when the lift plate does not fit the top of the transmission case for 6T30, 6T35, 6T40, 6T45, and 6T50 Transmissions.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2018 GMC Acadia has a pervasive electrical defect in the transmission position sensor. Owners place the vehicle in park, but the electronics refuse to recognize it. The "Shift to Park" warning appears on the dash even though the shifter is physically in the park position. The engine will not shut off, the battery drains, doors will not lock, and lights stay on. Owners describe having to repeatedly shift between gears, restart the vehicle multiple times, or even jiggle the shifter violently—sometimes bruising wrists—before the system finally acknowledges park and allows shutdown. Some vehicles roll backward even after the shifter is engaged. Dealers cite TSBs 19-NA-206 and 19-NA-205 as fixes and recommend replacing the shifter harness (~$300) or entire shifter assembly (~$500-$1,000+). Many owners report the same failure recurring within months or a few years, even after repairs.
Separately, transmission failures plague these vehicles. Owners report the transmission slipping or jerking when shifting from second to third gear while warm, causing sudden engine RPM spikes and brief loss of throttle response. On other occasions, the transmission fails to shift entirely while driving at highway speeds, losing all power. Full transmission replacement runs $7,700–$10,000. One owner had the valve assembly replaced at 35,000 miles with no lasting fix; dealers then refuse to cover another replacement.
Once the shift-to-park sensor fails, secondary electrical failures cascade: loss of power steering, ABS, StabiliTrak, AWD, and power surges that can cause loss of vehicle control. Owners also report door locks that randomly lock and unlock, radiator fans that run constantly with no cooling, brake pedals that sink to the floor, and persistent engine noise with uncontrolled acceleration on some vehicles. GM has issued technical service bulletins and limited recalls on some vehicles but excludes many 2018 Acadias despite identical complaints. Repairs made under warranty often fail again shortly after warranty expiration, leaving owners to pay out of pocket for the same parts and labor.
Same GMC Acadia powertrain reports on nearby years: 2016 · 2017 · 2019 · 2020 · 2021
Failure modes owners describe
Shift to Park Detection Failure
Transmission sensor fails to recognize vehicle is in park position, causing 'Shift to Park' warning message and preventing vehicle shutdown. Gear shifter physically in park but electrical system does not register it.
When: Ranges from early ownership (8k-11k miles) to higher mileage (120k miles); most commonly reported between 31k-70k miles
Symptoms owners cite: Shift to Park warning message displayed despite gear physically in park; Vehicle will not shut off or power down completely; Continuous audible beeping/chiming alarm; Interior and headlights remain illuminated; Doors will not lock; Requires repeatedly shifting between gears and restarting vehicle multiple times to resolve; Battery drain from inability to fully power down; Vehicle rolling after apparent park engagement
Codes mentioned: TSB 19-NA-206, TSB 19-NA-205, NHTSA Campaign 17V516000
Repairs/costs cited: Dealer repairs include: shifter harness replacement (~$300), shifter assembly replacement (~$500-1000+), shift control module replacement, inline shifter wiring harness replacement, shift column replacement. Multiple owners report repeat failures after initial repair with same or similar parts.
Recalls/TSBs owners mention: GM issued TSBs 19-NA-206 and 19-NA-205 for this issue. Some vehicles covered under recall 17V516000, but many 2018 Acadias not included despite having identical symptoms. GM goodwill repairs noted in some cases but inconsistently applied. Warranty typically expires at 36,000 miles or 3 years, leaving owners without coverage if failure occurs after warranty period.
Transmission Shift/Slip Defect
Transmission slips or fails to shift smoothly between gears, particularly 2nd to 3rd gear transition when warm, causing engine RPM spikes and loss of throttle response during shift. On other occasions transmission jerks, fails to shift, or loses power entirely while driving.
When: Occurs when transmission is warm; reported from 35k to 120k miles
Symptoms owners cite: Loud engine revving (500-1000 RPM) during gear transition without vehicle acceleration; Loss of throttle response for 0.5-1 full second during shift; Transmission jerking and not changing gears; Vehicle nearly unresponsive to accelerator input during shift event; No check engine light in many cases despite transmission malfunction; Sudden loss of power while driving at highway speeds; Inability to shift into drive or reverse on some occasions; Engine revs but vehicle will not move forward
Repairs/costs cited: Dealers replaced valve assembly at 35k miles with repeated failures. One estimate for full transmission replacement: $7,769 with 3-year/100,000-mile warranty. Another owner cited ~$10,000 transmission replacement. Many repairs unsuccessful; dealers offer either same part replacement or warranty extension but not both.
Recalls/TSBs owners mention: GM technical assistance provides minimal guidance. Service managers admit problem exists but GM denies technical support in resolving root cause. One owner reports GM refuses to cover full transmission replacement, only extending warranty on existing transmission.
Secondary Electrical Failures Following Shift to Park Issue
Once primary 'Shift to Park' issue triggers electrical problems, vehicle experiences cascading electrical system failures including loss of power steering, AWD, ABS, StabiliTrak, and additional drivetrain component malfunctions.
When: Occurs after primary shift-to-park failure; reported from 36k+ miles
Symptoms owners cite: Loss of power steering; Loss of AWD function; Loss of StabiliTrak stability control; Loss of ABS braking; Braking system errors; Power surges causing loss of vehicle control; Dashboard and instrument cluster malfunctions; Navigation system failures; Vehicle rolling despite being in park; Electrical system drain/battery death
Repairs/costs cited: No specific repairs cited for secondary failures in narratives; owners report needing entire system diagnostics and multiple component replacements.
Brake Pedal Defect
Brake pedal depresses to floorboard without warning, reducing braking effectiveness. Multiple rotors require replacement; issue persists even after rotor replacement.
When: Reported around 46k miles
Symptoms owners cite: Brake pedal depresses fully to floorboard without warning; Reduced braking responsiveness
Repairs/costs cited: Initial diagnosis: all four rotors needed replacement. Later diagnosis: only one rotor needed replacement. Even after rotor replacement, failure persisted.
Engine Noise and Unexpected Acceleration
Vehicle produces loud lawnmower/crackling noise in rear muffler area during acceleration; on separate occasions vehicle suddenly accelerates uncontrollably with loud noise and jerking motion.
When: Since August 2018; reported early in ownership
Symptoms owners cite: Loud lawnmower/crackling sound from rear muffler during acceleration; Sudden uncontrolled acceleration with loud noise; Vehicle jerks and accelerates ~15 MPH faster than intended; Loss of brake control (brake only goes in so far); Inability to stop vehicle during acceleration event
Repairs/costs cited: Chevrolet dealership inspection found no identifiable cause for noise.
Stuck-in-Park/Stuck-in-Neutral Transmission Position
Transmission physically stuck in park position and will not shift to drive, or conversely vehicle stuck in neutral unable to move to park. Conflicts between actual transmission position and dashboard indicator.
When: Reported from 47k miles onward
Symptoms owners cite: Shifter frozen in park, cannot move to drive; Console indicates drive but shifter physically in park; Transmission stuck in neutral despite park commands; Cannot disengage from park to access drive; Inability to move vehicle despite pressing accelerator
Repairs/costs cited: Requires dealer towing for diagnosis; dealer reported shortage of technicians delaying repairs.
Engine Start/Restart Failure with Battery Drain
Vehicle fails to start or restart daily; requires jumpstarts. Appears linked to shift-to-park electrical issues preventing proper vehicle shutdown and draining battery.
When: Reported at 81,737 miles
Symptoms owners cite: Vehicle fails to start daily; Requires frequent jumpstarts; Battery drains despite vehicle appearing off; Engine switch failure detected
Repairs/costs cited: Testing at AutoZone, Firestone, and Pep Boys could not determine cause. Pep Boys determined engine switch had failed. Dealers unable to diagnose.
Recalls/TSBs owners mention: GM advised owner to file NHTSA complaint rather than offering service support.
Radiator Fan and Cooling System Malfunction
Radiator fan runs continuously on high, AC stops cooling, thermostat gauge drops to C, power steering assist reduced. No check engine light despite malfunction. Resets randomly without repair.
When: Reported for over one year; occurring more frequently after vehicle out of warranty
Symptoms owners cite: Radiator fan runs on high constantly; AC stops blowing cold air; Thermostat gauge drops to cold (C); Power assist reduced message appears on dash; No check engine light despite failures; Random resets with temporary normal function; No diagnostic codes available
Repairs/costs cited: Dealership serviced vehicle but never addressed issue as problem. No repair performed.
Door Lock Electrical Failure
Power door locks malfunction, automatically locking and unlocking at random. Vehicle doors lock owner in or out unpredictably, requiring climbing through windows or trunk access.
When: Reported as ongoing issue
Symptoms owners cite: Doors automatically lock and unlock at random; Locks owner in vehicle; Locks owner out of vehicle; Requires climbing through windows to escape; Requires leaving windows open for access
Repairs/costs cited: GM replaced computer in vehicle but issue persisted. Testing performed and brought to GM.
Recalls/TSBs owners mention: GM replaced vehicle computer but did not resolve issue.
Synthesized from 155 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 8 most recent
The contact owns a 2018 GMC Acadia. The contact stated that on three separate occasions while driving at undisclosed speeds, the gears inadvertently shifted from second gear to third gear and then to neutral. No warning lights were illuminated. The vehicle was taken to the dealer on three separate occasions where the failure could not be duplicated. The vehicle was then taken back a fourth time…
2018 GMC acadia. The crossover (automatic gear shifter) is failing to recognize that it has been put into park, flashing a message on the dash instructing the driver to 'shift to park' even when the gear lever have already been moved to the 'p' position.
When I put the in park, it does not recognize that the vehicle is already engaged. The console displays tells me to put vehicle in park and beeps. I have to keep moving the gear shift from reverse to neutral to park several times before it recognizes the vehicle in engaged in park. This has been happening about 8 months or so. I have mentioned it to the dealer and they tell me their are no…
Shift to park message has appeared again and the engine will not cut off. First happened in Feb 2020, mileage was 31,143. Took to Dealer and new wiring harness was installed. Had to take back to dealer April 2020 for same problem; shifter assembly was replaced at that time. Shift to park message came back on August 2023. Took back to Dealer and shifter harness replaced again and jumper harness…
Recevied "action required - shift to park" message on instrument panel screen. Motor turns off but vehicle stays in accessory mode and chimes continuously. Dealer replaced wiring harness that promised to fix the problem, went away for 1 month and came back. Jiggling the shifter or flicking the shifter button is the only way it will go away.
The contact owns a 2018 GMC Acadia. The contact stated that after shifting to the park(P), there was an audible warning alarm activated, and the message "Shift to Park" was displayed, and the vehicle failed to immediately turn off. After restarting the vehicle and jiggling the gear shifter, the failure was corrected. The vehicle was taken to the local dealer, who diagnosed the vehicle and…
Experienced the "vehicle not in park " when shifter was in park. Engine would not turn off because electrical switch did not recognize the vehicle was in park. After many tries I was able to turn vehicle off. Had vehicle serviced and shifter was replaced (3 weeks ago ). Today shifter froze in park yet console indicated vehicle was in drive. Did not remove foot off of brake because vehicle would…
11/22/24 shift to park issue appeared. Happens constantly. I just bought car on 10/26/2024. I know by looking up shift to park issues there was a recall on 2017 an 2018 cars.
Had powertrain trouble with your 2018 GMC Acadia?
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 Acadia?
It's a documented issue but not catastrophic. 155 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Across the 89 complaints that reported odometer mileage, most powertrain failures cluster between 20,000 and 48,000 miles, with the median around 37,000. A quarter of owners report trouble before 20,000; a quarter make it past 48,000. 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/Acadia.
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.