2019 GMC Acadia: engine overheating

Filed Sep 14, 2026 · Engine, Steering · LA

I am submitting this complaint to request that the federal safety agency 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.

Filed Jul 29, 2026 · Steering · ME

I am submitting this complaint to request that the federal safety agency 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 61,500 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. When the coolant-temperature signal becomes invalid, this function can become inoperative, potentially resulting in a heavier-than-normal steering feel.

Filed Jun 27, 2026 · Engine · PA

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.

Filed Sep 7, 2023 · Engine, Steering · 70,000 miles · NH

The contact owns a 2019 GMC Acadia. The contact stated while driving 55 MPH, the electric power steering (EPS) warning light illuminated, displaying the message "Steering assist Might be Inoperable". The contact stated that following the message being displayed, the vehicle overheated. After restarting the vehicle, the vehicle returned to normal functionality, but the failure had since become a regular occurrence. The vehicle was taken to the dealer, who diagnosed a failure with the thermostat. The vehicle was repaired. The manufacturer was notified of the failure but referred the contact to the federal safety agency Hotline for assistance. The failure mileage was 70,000

Filed Jun 1, 2023 · Engine · MI

Thermostat gets stuck, generally in open state. AC also is disabled in this condition, soft code (no MIL) mentions "limited steering available" and temp gauge on dash goes to 0. Hard code eventually comes (solid Check Engine light on the dash). Code, MIL, and temp gauge can be cleared and fixed by disconnecting battery negative terminal and reconnecting it, and it will run consistently for a while, though it will return. Online there are no thermostat modules for this engine available (3.6L V6, also in Cadillac XT6, Buick Enclave, and Chevrolet Traverse) showing that thermostat replacement is widespread. Online forum searches also describe widespread thermostat issues for this engine, at roughly $1200 per fix. A reliable thermostat is critical for long-term engine functionality, and should not need replacement at half of design life (~75-80k miles). Though this one tends to fail open instead of close, overcooling of an engine still could have its own issues, and failing closed could lead to engine overheating.