Engine And Engine Cooling Problems of GMC Acadia - part 1

Engine cooling system malfunction, ive had to receive maintenance on my Acadia 2025 elevation 3 times in the pass 2 months for the same issue, the coolant system. This is becoming a reoccurring issue that needs to be investigated thoroughly. Ive had to get a rental car all 3 times, and this is becoming frustrating and financially draining. My biggest concern is what is to happen once my warranty expires? guess I'll be paying a note and repair cost until a recall is opened on this issue and then will have to wait for reimbursement. This is horrible to say this car was made 2 years ago. Attention is needed on this defective part. I'm so frustrated to I might just trade in this vehicle. I pay for dependability and reliability in the amount of 1300. 00 monthly, but only receiving a financial headache.

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Today, on [xxx] outside of sapulpa oklahoma, while in the inside lane of three southbound lanes, cruise control on at 80mph. The car suddenly reduced power, air conditioning stopped, assisted power brakes stopped working, gauge cluster full of flashing warnings. Pulled to the right shoulder, stopped with difficulty. Had to pump and stand on brakes to get stopped. Shut off engine, then restated and everything stated working again. Scary situation in heavy traffic. Lucky to be alive!! information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

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2020 GMC Acadia bucks/hesitates when I take off or slow down and speed back up. Mechanic looked at it can see engine is having random misfires. We have tried plugs, transmission fluid, looked at everything we could think of. The condition improves if I put into awd but still exists and worsens for a period of time after it shifts back into fwd mode. My mechanic has done a lot of research and found that one possible issue was a stretched timing chain but since it is out of warranty I just couldn't afford to have them tear it down it is an enormous job to see if that was the issue. It also lines up with other known issues like the auto stop issues and possibly a fuel pump issue. I have seen many people complaining online about this particular issue but not many on here and no recalls on my vehicle regarding the known issues.

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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.

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Oil leaks from the timing cover on the top and bottom.

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Engine coolant thermostat failed open. Resulting in reduced steering capabilities, and no ac.

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.

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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.

See attached file.

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.

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.

“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.

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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.

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.

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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!.

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.

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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.

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Blind spot monitor goes off for everything. Engine has chirping noise. Brand new.

Hesitants and shudders when shifting into 2nd gear.

The contact owns a 2012 GMC Acadia. The contact stated that the vehicle failed to release from low gear while at a stop. The transmission was backed up. The engine light was illuminated. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted, who confirmed there were no recalls. The failure mileage was approximately 213,766.

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Steering assist is reduced brake assist reduced seems to be a defective thermostat and sensor . Temp gauge is below normal operating temperature this needs to be addressed by gm should be a recall as this can be a costly repair. Many reports of same issue.

The contact owns a 2019 GMC Acadia. The contact stated that while driving at an undisclosed speed, a “steering assist is reduced ” warning message unexpectedly displayed. The contact also stated that the thermostat became inoperable. Additionally, the thermostat information was no longer displayed on the instrument panel. The vehicle was taken to the dealer, where it was diagnosed that the thermostat had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA hotline for further assistance. The failure mileage was approximately 48,500.

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.

I am submitting this complaint regarding ongoing mechanical and electrical issues with my 2021 GMC Acadia that have been occurring intermittently for approximately the past year and a half. The primary issues involve the coolant temperature sensor, thermostat system, engine cooling fan, and dashboard warning messages. The vehicle repeatedly experiences problems related to the coolant temperature sensor and thermostat. During these episodes, the engine cooling fan continues running even after the vehicle has been turned off, sometimes for an extended period of time. In addition, the dashboard frequently displays the warning message: “steering assist is reduced – drive with care. ” these warning messages and symptoms occur off and on without consistent resolution. The vehicle has already undergone repairs, including replacement of the radiator, yet the problems continue to return. Despite previous service attempts, the underlying issue has not been permanently corrected. The recurring nature of these problems raises concerns about the reliability, safety, and dependability of the vehicle, especially considering the steering assist warning and possible overheating or electrical system concerns connected to the cooling system malfunction. The repeated failures have caused significant inconvenience, concern for safe operation of the vehicle, loss of confidence in the vehicle’s reliability, and ongoing disruption due to repeated repair needs. I am requesting a thorough diagnosis and permanent repair of the coolant temperature sensor, thermostat, cooling fan system, and any related electrical or control module issues contributing to these recurring problems.

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Bought the Acadia in June of 2021, in December of 2022 had to have the radiator replaced due to it leaking. This was found on routine maintenance and was not having any issues whatsoever. I received no alerts on my dash such as a check engine light. Fast forward to March 2026, I received a message of "steering assist reduced. Drive with care. " the engine seemed like it was still running despite the car being off. This was happening intermittently and definitely not every time I drove. I made an appointment for the regular oil change and to have this message investigated. Initially they told me it was the temperature regulator, however, they put a new regulator on and tried to re-pressurize the system. The system failed to re-pressurize due to the radiator leaking again. Of course, there was a 2 year warranty on the radiator after it was replaced initially and now we are about a 1. 5 years outside the warranty.

Coolant temperature sensor failed - it is still in the engine. The fan stays on high all the time. And the ac does not want to turn on. The car is extremely hot to drive in during the summer months. I have to transport persons who are seniors and in their mid 80s. It is not safe to drive this car in the summer. I can't tell if its over heating or what is happening. The coolant temperature gauge does not work. The dealer said my car is out of warranty and that the ac will not start until the sensor is replaced. I said that it has less than 50,000 miles. They will not help me. The vehicle has not been inspected anyone other than the service mechanic. The engine light start coming on about a month ago. I drove first to an autoparts store to see if they could help. This is the first time I learned that it could be a bad sensor.

The contact owns a 2020 GMC Acadia. The contact stated that while driving the vehicle, it stalled after initially adding fuel. Even though the reading indicated there was 1/8 of a tank of fuel. The fuel gauge failed to move. The thermostat was stuck open. The electric steering was not working properly. The engine light was illuminated. The traction control was turned off. The contact stated that the failure was related to NHTSA campaign number: 20v639000 (fuel system, gasoline). The contact stated that he was a master mechanic. The contact called the local dealer, but the vehicle was not diagnosed or repaired. The contact called two other local dealers, tadd jenkins chevy 409 farnsworth way, rigby, id 83442, and smith Chevrolet. Address: 3477 pioneer dr suite 200, idaho falls, id 83402. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 61,699.

The warning steering assist reduced, drive with caution appears. Shift to park appears. Temperature gauge drops to zero. Fan runs on high. A/c & heater don’t not work when this happens. We certainly do not feel safe driving our Acadia like this. Can’t trust that it won’t start on fire.

[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.

Engine randomly shuts off when driving for no reason. Will restart and check engine light comes on. Has now happened three times , twice to me in traffic. One of those the car went into a limp mode where it wouldn't drive above 30mph at most. This is very unsafe in the middle of highway traffic. The second happened approaching a traffic light , I put the car into neutral and luckily it restarted and check engine light came on. The third time my wife had her friends in the car and it shut off at a light , she had no idea what to do. I had her stay there and brought her our other car. I have read this is caused by a known fuse box issue. They should be made to fix this problem before someone gets seriously hurt driving in traffic.

Vehicle would not run due to a failed fuel pump control module. With a non-running engine, the transmission could not be placed into neutral to be able to movie vehicle out of the road. Needed tow truck to move vehicle. This condition placed many people at risk as the vehicle could not be moved out of the way until a tow truck arrived.

Thermostat issue causing check engine light as well as steering assist to be turned off. Fan constantly runs. Reset code and immediately is fine again for anywhere from a day to weeks but then happens again. Car is just out of warranty but seems to be common occurrence as there is a service bulletin for the 2021 model.

The vehicle has a serious transmission/drivetrain defect that repeatedly occurs when accelerating from a complete stop, especially onto an incline. The vehicle sometimes does not respond at all when the accelerator is pressed and fails to move, even though acceleration is being requested. In one recent incident, it remained stopped for about one minute before finally responding. During these events, the vehicle jerks and shakes severely and fails to gain speed as expected. This creates a major safety risk at stop signs, intersections, and uphill starts because the vehicle may not move when needed and cannot keep up with traffic. The problem has worsened, and during one of these incidents the check engine light came on. I have video evidence showing the loss of response to accelerator input, severe jerking/shaking, and the check engine light illuminating during the same event. The issue has been reported to dealers and gm customer service but has not been properly resolved.

I purchased this vehicle in June 2024 as a demo vehicle with approximately 7,000 miles on it. Within one month of ownership, the vehicle began experiencing serious problems that have continued to worsen. The vehicle currently has approximately 34,000 miles, and the issues have been ongoing from the time of purchase through the present. Since purchasing the vehicle, it has been in the dealership multiple times for the same recurring problems, including but not limited * powertrain issues and loss of power * reduced acceleration while driving * complete electrical failure while driving * engine and electrical warning lights repeatedly turning on * vehicle running excessively hot * water pump replacement * replacement of sensors * thermostat replacement * ongoing engine and electrical system malfunctions despite these repairs, the same problems continue to reoccur. Each time I return the vehicle for service, I am informed that it is a “different issue,” even though the symptoms remain unchanged. This strongly indicates a defective powertrain and/or electrical system that has not been properly repaired. The most serious concern occurred while I was driving on public streets, when the vehicle lost acceleration, electrical power shut off, and the vehicle completely shut down, nearly causing me to be hit by other vehicles. This incident created an extreme safety hazard for myself, my passengers, and other motorists. I have made several formal complaints directly with GMC, and more than four case numbers have already been created regarding this vehicle. Despite these complaints and repeated repair attempts, the problems persist. Given the repeated failures, numerous repair attempts, documented safety risks, and the fact that these issues began shortly after purchase, I believe this vehicle qualifies for relief under applicable lemon laws and consumer protection laws. Incident (critical)vehicle lost acceleration and electrical power and completely stalled while roads.

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.