I am submitting this complaint to request that NHTSA investigate a potential safety defect involving the engine coolant temperature monitoring system, thermostat/engine coolant temperature sensor system, and its relationship to reduced steering assist in 2019 GMC Acadia vehicles. My 2019 GMC Acadia, currently at approximately 91,500 miles, has experienced the following symptoms: • The engine temperature gauge remains flat or reads abnormally low/cold. • The cooling fans run continuously at extremely high speed, creating a loud "screaming" fan noise. • The vehicle displays the warning message "Steering Assist is Reduced — Drive with Care." • The vehicle has a history of diagnostic trouble code P0128, "Engine Coolant Temperature Below Thermostat Regulating Temperature." I am concerned that these symptoms are related and represent a potential safety defect rather than an isolated thermostat or cooling-system repair. GM has issued bulletin PIT5967, "Service Steering Message With P0128," which applies to GMC Acadia vehicles from model years 2017 through 2023. The bulletin states that when P0128 is present, the ECM may be reading coolant temperature incorrectly and that a "Service Steering Message" may be displayed to protect the steering gear in the event of an undetected overheating condition. GM instructs technicians to diagnose and repair P0128 first. GM bulletin 17-NA-158 also describes a relationship between P0128, an invalid coolant-temperature signal, and the "Steering Assist Reduced, Drive With Care" warning. The bulletin explains that the steering module relies on valid coolant-temperature information to provide additional steering assistance under cold conditions. Also will not register when put in park. Getting error message "shift to park" take multiple restarts of the vehicle and shifting gear back and forth for it to register.
NHTSA complaint #11764000 — an unverified report by a vehicle owner.
The car will frequently but not always fail to shut off when the start/stop button is pushed while in Park. The message "shift to park" come up on the display and a yellow light comes on in the button. I have to restart the engine and it often takes as many as 10 attempts to finally shut off the engine. Between each attempt I have to shift the transmission out of park and back into park. This has been happening for more than a month.
NHTSA complaint #11763610 — an unverified report by a vehicle owner.
Technician told me the engine "grenaded itself". "Cylinder #4 melted into the side walls of the cylinder wall caused by air to fuel mix ratio controlled by the ECU failure to mix appropriately." My family and I were traveling for Easter and were stranded on the side of the highway. I had a private repair shop (Greenville Auto Clinic LLC) confirm as well as the local dealership Greenville Chevy. The vehicle required an engine replacement. I did contact GMC's Zone Manager out of Atlanta, GA for assistance, he reduced the bill from over $10,000 down to $6098. There was no error messaging, only an engine that would not respond to the accelerator pedal. The engine would try to accelerate, but struggled to the point it would die when I applied too much pressure on the gas pedal.
NHTSA complaint #11760423 — an unverified report by a vehicle owner.
2015 gmc Acadia, vin ending 7457,p2635,stuttering/hesitation and engine stalling when Arizona temperatures exceed 100* f , and mechanic advising that the condition corresponded to a known gmc issue for which they could not obtain an applicable corrective part / repair
NHTSA complaint #11758928 — an unverified report by a vehicle owner.
Received a power steering reduced notice when starting the car, noticed shortly after driving the temperature gauge had not moved from its resting position. A few trips later it still had not moved and the check engine light came on. Mechanic looked at it said it may be a sensor quoted $1k to fix. A few days later it randomly started working and the light went off so I did not have it fixed. About 4 months later the same code displayed on the dash with the same issues. This time I noticed the ac would not work either it only blew out hot air. Also the fan under the hood turns on as soon as the car is started. Been about 3 days and it started working again out of nowhere.
NHTSA complaint #11758890 — an unverified report by a vehicle owner.
The contact owns a 2019 GMC Acadia. The contact stated that while driving at an undisclosed speed, the engine seized, with several unknown warning lights illuminated. Additionally, the battery low and steering assist warning lights were illuminated. The contact's minor children were occupants in the vehicle during the failure. The tow truck assistant arrived. The tow truck driver assisted with restarting the vehicle. The contact was able to restart the vehicle. The vehicle was taken to Firestone; however, the failure was not duplicated. The contact stated that a portable diagnostic tester was attached, but no error codes were displayed. The failure reoccurred. The vehicle was taken back to Firestone, where it was diagnosed with a failed START/STOP module. The contact was informed about Technical Service Bulletin: 21-NA-139. 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 81,126.
NHTSA complaint #11757418 — an unverified report by a vehicle owner.
The contact owns a 2019 GMC Acadia. The contact stated that while driving at an undisclosed speed, the transmission failed to properly shift gears and the vehicle failed to exceed 40 MPH while driving. The contact stated that the transmission failed to shift above third gear. The check engine warning light was illuminated. The vehicle was taken to an independent mechanic, who discovered that there was no transmission fluid inside the torque converter. The vehicle was scanned and displayed an issue with the transmission control module. The local dealer was contacted and confirmed that the VIN was not included in NHTSA Campaign Number: 20V668000 (Power Train). The vehicle was not diagnosed or repaired. The manufacturer was contacted and referred the contact to the NHTSA Hotline to report the failure. The approximate failure mileage was 154,429.
NHTSA complaint #11754373 — an unverified report by a vehicle owner.
I was at a red light, I went to drive as the light turned green and my car stopped and wouldn’t drive, I could go into neutral to get out of way but anything the car would stop. There is no codes or lights turned on my dash though.
NHTSA complaint #11753750 — an unverified report by a vehicle owner.
My Acadia went into limp Mode displaying low power mode on the screen and wouldn’t start for a couple days after. Lights started illuminating on the dash as abs, traction control, and stanilitrack, then check engine light came on and my gmc app displayed code p2138. I have had since low power and extremely high gas consumption.
NHTSA complaint #11751463 — an unverified report by a vehicle owner.
“Steering Assist is Reduced” warning, P0128 code, thermostat-related symptoms, increased steering effort or other safety concerns while driving. This issue required increased steering effort and affected my wife's driving ability to respond to changing traffic conditions. This is most likely a faulty thermostat housing assembly. This has been well documented temperature gauge problems, cooling system issues, and related warning messages. Our GMC Acadia is a 2022 AT4 with 53,500 miles. GM recently issued Special Coverage N252508350 for 2021 Acadias with the 3.6L LGX engine affected by thermostat housing issues. Owners of other model years reporting substantially similar symptoms remain responsible for the repair cost. Please investigate this.
NHTSA complaint #11750068 — an unverified report by a vehicle owner.
[Symptom & Safety Hazard] While driving my 2020 GMC Acadia 3.6L V6, the Driver Information Center displayed the warning: "Steering Assist Reduced, Drive With Care" (SARDWC). Steering effort increased abruptly, the engine temperature gauge dropped to cold/zero, and the HVAC system lost air-conditioning function. The warning and reduction in steering assist presented a safety hazard and increased the risk of a crash. [Diagnostic Findings] Vehicle diagnostics identified DTC P0128 - Engine Coolant Temperature Below Thermostat Regulating Temperature. A GMC Certified Dealer technician diagnosed a failed engine coolant thermostat housing assembly. [Manufacturer Information] GM documentation links DTC P0128 and invalid engine coolant temperature signals to the "SARDWC" condition. GM Bulletin 17-NA-158 states the “SARDWC” condition is caused by an invalid coolant temperature signal and the steering module relies on coolant temperature information for steering-assist compensation. GM bulletin PIT5967 directs technicians to diagnose and repair DTC P0128 when the warning message is present. In Oct 2025, GM issued N252508350 for 2021 Acadia vehicles equipped with the 3.6L LGX engine due to an engine coolant thermostat condition. My 2020 Acadia is part of the same generation vehicle platform and is equipped with the same 3.6L LGX engine. It experienced the same thermostat-related failure symptoms, including DTC P0128 and the "SARDWC” warning. [Reason for Complaint] I am filing this complaint because a thermostat-related cooling-system failure resulted in a steering-assist warning and reduction in steering assist while the vehicle was being driven. Moreover, GM issued N252508350 for 2021 Acadia vehicles equipped with the 3.6L LGX engine due to the same engine coolant thermostat condition, yet similarly affected 2020 Acadia vehicles are not included. NHTSA should investigate whether additional 2020 vehicles are experiencing the same failure sequence and resulting safety risk.
NHTSA complaint #11749841 — an unverified report by a vehicle owner.
Shortly after purchasing my 2019 GMC Acadia with approximately 52,000 miles, the vehicle displayed a "Steering Assist is Reduced. Drive with Care." warning message and illuminated the check engine light with diagnostic code P0128 00 (Engine Coolant Temperature Below Thermostat Regulating Temperature). I disconnected and reconnected the battery, after which both the warning message and check engine light disappeared. However, the engine coolant temperature gauge then began behaving erratically. On multiple cold starts, the gauge would immediately indicate that the engine was already at normal operating temperature even though the engine had been sitting long enough to be completely cold. This led to a diagnosis of a thermostat and/or engine coolant temperature sensor failure. After researching the issue, I found many other owners reporting the same thermostat and engine coolant temperature sensor failures. I believe this is a widespread defect that should be investigated because incorrect coolant temperature readings can prevent the driver from knowing the true engine temperature and may result in improper engine temperature regulation, overheating, and possible engine damage.
NHTSA complaint #11746957 — an unverified report by a vehicle owner.
Thermostat and cooling sensor went out on my car. GMC issued a special coverage bulletin for 2021 Acadia since it's a widespread issue but not the 2020 (mine) which is also a widespread issue looking online. The repair is over $1000 and should be covered!
NHTSA complaint #11745760 — an unverified report by a vehicle owner.
The contact owns a 2010 GMC Acadia. The contact stated that while driving at an undisclosed speed, there was an abnormal sound coming from the vehicle. The contact became aware of white smoke coming from the vents. No warning lights were illuminated. The vehicle was driven to the shoulder of the road. The contact and minor children exited the vehicle. The contact stated that while exiting the vehicle, there was fire coming from underneath the hood. The Fire truck arrived on the scene and extinguished the fire. The vehicle was towed to a local tow yard. The vehicle had liability coverage, and the insurance company declined to inspect the vehicle. The contact stated that the vehicle was a total loss. The failure had occurred while the contact's minor children were seated in the rear seat of the vehicle. The contact and the children sustained smoke-related injuries. The contact and the children later received medical treatment for the smoke-related injuries. The manufacturer was made aware of the failure, and a case was filed. The manufacturer declined to inspect the vehicle. The failure mileage was approximately 163,000.
NHTSA complaint #11744975 — an unverified report by a vehicle owner.
The contact owns a 2014 GMC Acadia. The contact stated that while in park(P), the vehicle rolled, requiring the driver to turn off and restart the vehicle, and the vehicle successfully shifted in park(P). Additionally, the contact stated that while driving at various speeds, the vehicle jerked. The contact stated that while driving 60-65 MPH, the vehicle shut off, and the steering wheel and the wheels locked up. The contact was barely able to pull over to the side of the road, where the contact waited before restarting the vehicle. The contact stated that the Check Engine warning light was recently illuminated. The vehicle was towed to two independent mechanics, where several diagnostic trouble codes associated with the transmission and the transmission module and solenoid were retrieved. The contact was then referred to a transmission specialist, where the vehicle was towed and was being diagnosed. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was approximately 160,000.
NHTSA complaint #11744114 — an unverified report by a vehicle owner.