There are 7 owner-reported engine complaints for the 2018 GMC Acadiain NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
The contact owns a 2018 GMC Acadia. The contact stated that while driving at an undisclosed speed, the vehicle failed to accelerate while attempting to shift gears. The contact stated that the vehicle jerked and made an abnormal sound, with the check engine warning light illuminated. Additionally, the contact stated there was black and white smoke coming from the rear of the vehicle. The vehicle was taken to the dealer, where it was diagnosed with transmission, cooling system, and fuel system failures. The dealer also determined that the engine was leaking oil. The dealer informed the contact that the vehicle required several repairs. The vehicle was not yet repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 126,000.
A warning popped up on my dashboard stating "Power steering reduced. Drive with care." multiple times. Whenever the warning popped up, my air conditioning would stop working and my engine fan would run very loud. The warning would go off and back on over the course of a year. This started in the beginning of summer, 2024. On 4/3/25 I took it into an auto mechanic shop and after they looked at this warning, they confirmed that the thermostat has an issue where it gets stuck in the "open" position, therefore the thermostat isn't working properly and my car thinks it's over heating, when it's really not. If my car were to overheat while this thermostat wasn't working properly, my engine could overheat or worse. The thermostat part is being replaced today so after today, it won't be available for inspection upon request.
The thermostat housing fails and is a known issue which causes the car to overheat and they said it will start of fire or shut down and loss of steering assist. The dealerships know about the issue and GMC does nothing leaving people with large repair bills or inoperable cars. the system won't let me upload my receipts here is the part #12678780 I was told by the dealership this is a known issue and they my emissions warranty only covers the thermostat but not the housing, but that they are 1 piece, playing games.....
bad torque converter lead to transmission replacement bad torque converter inspected by dealer car stopped starting difficulty shifting and catching up to speed while driving gmc california denied goodwill help
A thermostat failure displays a "steering assist" warning while driving. The thermostat housing has been replaced twice in 3 years after this warning.
WHENEVER I SHIFT FROM DRIVER OR REVERSE INTO PARK MY CAR ISN'T REGISTERING THAT I SHIFTED TO PARK AND IF GIVING ME THE MESSAGE OF 'SHIFT TO PARK'. I HAD TO SHIFT FROM DRIVE TO PARK AT LEAST 4 TIMES TO BE ABLE TO GET MY CAR TO RECOGNIZE THAT MY CAR WAS IN PARK AND SO I COULD TURN OFF MY CAR.
"SHIFT TO PARK" ERROR 90% OF THE TIME WHEN I ATTEMPT TO SHUT THE VEHICLE OFF. IT IS IN PARK AND IT'S NOT RECOGNIZED AS BEING IN PARK. IT CAN TAKE ME ANYWHERE FROM 30 SECONDS TO 5 MINUTES TO JIGGLE IT THE RIGHT WAY TO GET IT TO REGISTER. PROBLEM IS UNTIL IT DOES REGISTER IN PARK I CAN'T SECURE THE VEHICLE. AND IT DINGS NONSTOP DRAINING THE BATTERY. I UNDERSTAND GM IS AWARE OF THE ISSUE AND DOESN'T HAVE A FIX. IT NEEDS A NEW TRANSMISSION IN MY OPINION. I'M STUCK IN A LEASE PAYING FOR A CAR THAT ISN'T SAFE FOR ME. IT JUST STARTED 6 DAYS AGO AND HAS ALREADY OCCURRED MORE THAN 2 DOZEN OCCASIONS.
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 26, 2026