What 386 owners told NHTSA about the 2018 GMC Acadia

Hesitants and Shudders when shifting into 2nd gear.

NHTSA ODI 11748054

I am getting the known P0128 code. My engine says it's cold when it's not, my AC isn't working, and I am getting a message that says "Steer assist reduced. Drive with care". This is a known problem and complaint of the GMC Acadia.

NHTSA ODI 11738997

The vehicle has experienced repeated electrical and engine-related malfunctions, including random engine shutdowns while driving and random no-start conditions. The thermostat and cooling system failed and were replaced in 2024. Multiple sensors have failed. The braking system remains noisy even after brake replacement. The lane detection safety system does not provide audible alerts. The vehicle is currently operational and available for inspection upon request. How was your safety or the safety of others put at risk? The vehicle has randomly shut off while driving on both highways and city roads in Azle, Texas. This occurred while my two children were in the vehicle. When the engine shut off, there was a risk of losing power steering and braking assist, which could have caused an accident, especially at highway speeds and in traffic. Has the problem been reproduced or confirmed by a dealer or independent service center? The thermostat and cooling system failure were confirmed and repaired by a service center in 2024. Electrical and sensor issues have occurred repeatedly but have not been fully diagnosed or resolved. Brake noise persists despite replacement. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives, or others? UNKNOWN. The vehicle has been serviced by repair facilities, but the manufacturer has not provided a definitive diagnosis for the engine shutdown and electrical failures. Were there any warning lamps, messages, or other symptoms prior to the failure? When did they first appear? Yes. Various warning lights and symptoms appeared prior to failures, including cooling system warnings and sensor alerts. Electrical issues and battery failures have occurred repeatedly, with batteries lasting only 2–3 years. Symptoms began after purchase and have continued throughout ownership. Additional details The brakes have been noisy even after replacement, and the lane detection system does not produce audible warni

NHTSA ODI 11716369

The warning light for a steering assist needs service came on the dash. The dealer had a code (po128) that pertained to a bad thermostat and coolant temp. sensor. The steering assist could have failed, along with possible engine damage. The dealer replaced the thermostat and the coolant temp sensor. Their were no police or insurance reports needed.

NHTSA ODI 11706286

I have a 2018 GMC Acadia that is now displaying " shift to park " while the vehicle is in park. Upon extensive research I see GMC did issue a recall however, my particular VIN was not included. Its NOW displaying the error message which would lead me to believe it IS part of the recall. I called my local GMC dealership (Langhorne, PA.) and they said this was not covered since my VIN was not issues a recall.

NHTSA ODI 11658958

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.

NHTSA ODI 11652547

The contact owns a 2018 GMC Acadia. The contact stated that while driving at 60 MPH, the reduced engine power message was displayed. The RPM increased to high, and the engine revved. The accelerator pedal was depressed, but the vehicle failed to respond as needed. The contact stated that the failure was related to NHTSA Campaign Number: 18V358000 (Fuel System, Gasoline). The vehicle was taken to the local dealer, where it was determined that the high-pressure fuel pump needed to be replaced. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 98,000.

NHTSA ODI 11649181

Sold 2018 GMC Acadia by LEE GMC in auburn. Acadias shift to park was defective, dealership replaced before sale did not disclose, shift to park and transmission malfunctions occurred. I returned Acadia to the dealership several times and they would never properly fix or address my concerns now my vehicle is unsafe to drive. I have documentation to support the claims in my letter, I can send as well if you’d like. Thank you Will send attachment

NHTSA ODI 11647553

Truck lost power randomly while driving on freeway spend so much money on fixing it this has to do something with the way the built it

NHTSA ODI 11645879

While car is in park, I get the "Shift To Park" warning after driving the vehicle.

NHTSA ODI 11644415

A thermostat failure displays a "steering assist" warning while driving. The thermostat housing has been replaced twice in 3 years after this warning.

NHTSA ODI 11635194

My steering assist is coming on an the thermostat play apart in this. The thermostat need to be change. 2018-GMC-Acadia are having problems with these parts.

NHTSA ODI 11625851

Steering Assist is Reduced Drive with care. Everyone is have a problem with the 2018-GMC-Acadia thermostat is bad.

NHTSA ODI 11624491

Seemingly at random a warning will pop up on the driver dashboard “Steering assist is reduced at this time”. This will lead to a engine coolant temp reading of 0 degrees, no a/c and reduced steering functionality. Through further investigation the OBD code P0128 tells us it’s a faulty Thermostat or Thermostat sensor. Even if you get these parts replaced, the issue still comes back. I’ve seen these exact complaints at least a thousand times across multiple years of this model/make 2016,2017,2018,2019. This is clearly a manufacturers fault and needs a recall before people get hurt.

NHTSA ODI 11593543

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.....

NHTSA ODI 11589301

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

NHTSA ODI 11588487

I have this 2018 Acadia where all of a sudden, at random, the radiator fan runs on high constantly, the AC stops blowing cold air, the thermostat gauge on the dash drops to the C, and the Power Assist is reduced and pops up as a message on the dash as well. Sounds like this may be a common problem among Acadia's. It resets at random and everything appears to be normal for a while. In addition, there are no check engine lights and no codes to check. I have had this happening for over a year and had a dealership service the car but never said mentioned it as a problem. So now that it's out of warranty my and has more frequent occurrences now I''m more aware but now it's out of warranty. It comes up on an Acadia Forum as a common issue. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11584108

I bought a used 2018 GMC Acadia in Oct. 2023. Initially the thermostat would go out and a check engine light would come on. This seems to be a common problem in GMC Acadia's and there are multiple blogs on this online (e.g. [XXX] ). INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11575479

The “steering assist reduced. Drive with care” A/C turns off and fan kicks on high. Transmission temp flatlines. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11554958

We own a 2018 GMC Acadia Denali. Upon shifting the vehicle into park, we cannot turn off the engine. The vehicle gives us a "Shift to Park" message on the instrument panel. As a result, we are unable to shut off our engine and, to avoid the battery running out, are forced to attempt to move the shift lever in and out of "Park" to get the car to detect that the shift lever is in fact in ‘Park.’”

NHTSA ODI 11516296

VEHICLE WILL NOT SHUT OFF AS IT SHOWS SHIFT TO PARK. REOCCURRING PROBLEM.

NHTSA ODI 11408404

MY CAR KEEPS GIVING NOTICE OF IT NOT BEING IN PARK, WHEN ITS CLEARLY SHIFTED INTO PARK. IT WONT SHUT DOWN, LET YOU LOCK DOORS. JUST BEEPS UNTIL IT FINALLY REALIZES ITS IN PARK. EVEN AFTER CONTINUOUSLY RE SHIFTING INTO PARK. WORSE IN THE SUMMER MONTHS. IT NEEDS TO BE FIXED AS MANY OTHERS ARE HAVING THE SAME ISSUE! *TR

NHTSA ODI 11329198

WHEN I SHIFT THE TO PARK AND TRY TO TURN OFF MY CAR THE SHIFT TO PARK LIGHTS UP AND I HAVE TO DOWN SHIFT AND THEN SHIFT TO PARK AGAIN TO GET MY CAR TO SHUT OFF ALSO THE AIR COMPRESSOR HAS ALREADY QUIT WORKING WITH LESS THAN 40K MILES ON IT. *TR

NHTSA ODI 11328481

VEHICLE WILL NOT ACKNOWLEDGE THAT IT IS IN PARK. FORCES ELECTRICAL TO STAY ON, AND SOMETIMES WILL NOT ENGAGE PARK SO VEHICLE CAN MOVE AS IF I'M NEUTRAL. HAS THUS FAR HAPPENED WITH VEHICLE STOPPED, BUT YOU CAN SOMETIMES SHUT OFF ENGINE AND EXIT VEHICLE WHEN IT IS NOT IN PARK AND CAN ROLL AGAINST YOU, OR ON KIDS EXITING ETC. VEHICLE ROLLED IN GARAGE AND STRUCK, AND COULD HAVE CRUSHED CHILD AGAINST DOOR.

NHTSA ODI 11315398

PUT CAR IN PARK WENT TO KILL IT AND IT WONT TURN OFF SAYS SHIFT TO PARK IT IS IN PARK HAD TO DO THIS LIKE 10 TIMES ..TWICE TODAY..MY CAR WONT TURN OFF FINALLY GOT IT OFF. I HAVE ONLY HAD THIS 2018 ACADIA LEAD THAN 1 MTH.. I HAVE READ WHERE THIS IS A BIG MAJOR ISSUE.. WHAT DO I DO

NHTSA ODI 11302677