2019 GMC Acadia: check engine light

Filed Sep 18, 2026 · Engine · PA

I own a 2019 GMC Acadia equipped with the 3.6L V6 engine. VIN. See form above In 2025, the engine coolant thermostat failed on my vehicle and required replacement at my expense. I am submitting this complaint because I believe this may represent a recurring component problem affecting 2019 GMC Acadia vehicles and I would like the federal safety agency to determine whether the condition presents an unreasonable risk to motor vehicle safety. General Motors has published service information addressing thermostat-related conditions on GMC Acadia vehicles equipped with the 3.6L engine. GM has also issued special coverage for an engine coolant thermostat condition on certain GM vehicles. GM’s special coverage describes a thermostat that can open at a lower temperature than intended, resulting in a malfunction indicator/check-engine light and diagnostic trouble code, and in some cases causing the engine cooling fans to continue running after the vehicle is shut off. My 2019 Acadia uses the 3.6L engine and the thermostat assembly addressed in GM’s service information. Despite this, my 2019 model year is not included in the current extended thermostat coverage. There is also a second, independent occurrence involving the same model year. My father owns a separate 2019 GMC Acadia, and the thermostat on his vehicle also required replacement in 2026. These are two separate vehicles that experienced thermostat failures requiring replacement. I understand that a thermostat failure is not necessarily a safety defect by itself. However, I am concerned that a recurring failure of this component could potentially create a safety risk depending on the failure mode and resulting vehicle condition. I am therefore asking the federal safety agency to review the available consumer complaints, manufacturer service information, warranty data, and GM special-coverage actions to determine whether there is a safety-related defect affecting 2019 GMC Acadia vehicles equipped with the 3.6L engine.

Filed Aug 18, 2026 · Transmission · NJ

On XXX at 1:56pm, I took the vehicle to Jiffy Lube service center #810 for the "Quick Oil Change Service" which includes checking and filling the Tranmission/Axle fluid. Per the attached receipt the Transmission/Axle fluid was "OK", and the next service was recommended after 5,000 addtional miles from the then current mileage of 153,317. On the morning o XXX, the car began experiencing issues identical to vehicle recall the federal safety agency ID Number: 20V668000. The check engine light turned on and the vehicle could maintain proper propulsion. On XXX at 3:25pm EST, I took the vehicle to AutoZone store #01664, whose "FixFinder" computer diagnostic inicated code PO700 "Transmission Control Module Requested MIL Illumination". On XXX, I had the car towed to a private mechanic who inspected the Vehicle and indicated that the transmission had "no fluid" despite having the fluids verified by Jiffy Lube on XXX. The mechanic suggested there may be a GMC service issue that required GMC remediation to due faulty internals which resulted in the transmission fluid leakage and subsequent triggering of the transmission computer module and related propulsion failure. As of today XXX, the vehicle is experiencing the same condition as indicated in vehicle recall the federal safety agency ID Number: 20V668000, which is creating additonal risk of vehicular accident/crash and vehicle fire in the presence of the ignition source. The milage is now 155,520. I am requesting this vehicle be serviced as part of recall the federal safety agency ID Number: 20V668000, you can verify from the vehicle registration from the Divison of Motor Vehicles and via CarFax that I purchased this vehicle used, the vehiclee has at least 1 (maybe 2) prior owners. I am requesting the vehicle (VIN [XXX]) receive the mandated recall service which will resolve the afformentioned issues and remove the related risks for myself, my passengers and all other motorists who are sharing the road. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 3, 2026 · Engine, Transmission · 154,428 miles · NJ

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 the federal safety agency Campaign Number: 20V668000 (Power Train). The vehicle was not diagnosed or repaired. The manufacturer was contacted and referred the contact to the federal safety agency Hotline to report the failure. The approximate failure mileage was 154,429.

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 May 5, 2026 · Steering · MI

My check engine light is on there is a note that says steering assist is reduced. I took it to O’Reilly’s to get it scanned. The code that comes up is P0128 indicating that the coolant thermostat has a fault. There are other GMC‘s that have a recall for this, but apparently not mine.

Filed Apr 20, 2026 · Transmission · AL

The contact owns a 2019 GMC Acadia. The contact stated that upon parking and attempting to turn off the vehicle, the message "Shift to Park" was displayed. The contact restarted the vehicle and was able to successfully park and turn off the vehicle after several attempts. Additionally, while driving at various speeds, the vehicle intermittently failed to shift as intended. Additionally, the A/C system was inoperable while driving. The check engine warning light was illuminated. The vehicle was taken to the dealer, where it was determined that the cooler and thermostat needed to be replaced. The parts were replaced; however, the vehicle was not serviced for the transmission failures. The contact stated that the vehicle was difficult to start, and the doors failed to close intermittently. The vehicle was taken to the dealer, where the battery was replaced. The contact stated that the transmission failure persisted, and there was an abnormal odor coming from underneath the hood. The vehicle was not repaired. The manufacturer was notified of the failure, and a case was filed. The contact was referred to the federal safety agency Hotline to report the failure. The failure mileage was unknown.

Filed Mar 28, 2026 · Engine · KS

2019 GMC Acadia message: Action Required Steering Assist Is Reduced Drive with care Both power steering and AC affected, check engine light on, engine temperature gauge off

Filed Mar 24, 2026 · Brakes, Driver assistance · MS

It has the ABS lights on and tire traction light on check engine light on and given signs of failed transmission Slow to takeoff shuttering of transmission

Filed Mar 6, 2026 · Engine · NJ

Owner of a 2019 GMC Acadia Denali (VIN: [XXX] , current odometer ~87,164 miles), purchased new. In early February 2026, the check engine light came on. Independent diagnostic scan confirmed persistent P0420 code (“Catalyst System Efficiency Below Threshold Bank 1”) as current, history, pending, and permanent. Inspection showed the front exhaust pipe bracket had snapped, damaging the flex pipe and causing an exhaust leak. This failure mode directly triggers the P0420 code and requires replacement of the bracket and affected flex pipe section. This is a known recurring issue on GM’s Lambda-platform vehicles (shared platform, 3.6L V6 engine, and exhaust system design). GM Special Coverage Adjustment N212356540 covers 2019 Chevrolet Traverse and Buick Enclave models for front exhaust pipe bracket separation (resulting in pipe damage, holes, leaks, rattling, or efficiency codes), providing free repair for 15 years or 150,000 miles from in-service date, regardless of ownership. The failure on this Acadia is mechanically identical, yet the model is excluded from coverage despite matching part design and numerous similar owner complaints documented on the federal safety agency and BBB reports. Multiple attempts were made to resolve through the selling dealership (no response to service inquiries). Matter was escalated to GM Executive Resolution. GM required a redundant diagnostic scan at an authorized dealer (additional cost incurred), despite independent confirmation of the issue. GM ultimately denied any coverage, TSB applicability, goodwill assistance, or further support. The snapped bracket and resulting exhaust leak can produce noise, fumes in cabin, potential component damage, and emissions noncompliance via false/legitimate catalyst efficiency codes. Inconsistent application of coverage for the identical defect across equivalent Lambda-platform models raises concerns about a widespread safety/emissions issue affecting 2019 GMC Acadia. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Dec 29, 2025 · Driver assistance · TN

My Temp control sensor is causing my check engine light to come on. After reviewing the problem, It seems many owners have had this same problem nation wide. I,m simply adding to the complaints by other owners that this should be a recall problem since so many owners are having this same problem. I,ve only had this car for 2 weeks & like the vehicle very much but this is a per the mechanic that may be caused by the sensor being placed too close to the exhaust without better protection from the heat. Please take this into consideration & hopefully come up with an adequate protective cover

Filed Nov 25, 2025 · Engine · IL

Check Engine Light came on with message of "Steering Assist is Reduced Drive with Care". This same thing happened to my sister-in-laws 2019 Acadia 2 months earlier. Took it in right away to the dealership to find out it's the thermostat, it's a common/known issue and it isn't covered under my extended warranty and will cost ~$1300. I'm seeing this is a common issue for Acadia's and has not had a recall, don't understand why. It's one thing if this is a easy part to replace, but GM has made it so that most people now need a dealership or auto repair shop to fix it.

Filed Nov 24, 2025 · OH

Thermostat stuck open and a steering assist light came on engine temp needle at zero. Check engine light came on, Had to have thermostat and coolant engine temp sensor replaced