2020 GMC ACADIA Power Train Problems

1. Shift to Park failure, P0700/P187e internal sensor, causing me to have to get a rebuilt transmission. 10/2025 2. Transmission shudder/hard-shifting ongoing 2022-2025 3. Coolant/thermostat issues. Steering Assist Reduced" message, fans stay on HIGH, no AC, engine temp on ZERO ongoing since 2024 3. Start/Stop button failure multiple times (replaced 3 times) 4. Rack and pinion/steering gear (would not return/ got stuck while turning) got new rack and pinion 2023 5. Water pump leaking, replaced 4/2024 6. Since 2023, have had ongoing “Timing OVER ADVANCED”, warning issues since 2023. This is TOO MUCH for a New car!!! I’ve owned MANY cars and NEVER had this many issues!!! There appears to be multiple design flaws with this model and similar models!

I own a 2020 GMC Acadia that has experienced multiple major mechanical failures within one year. In January 2025, at around 74,000 miles, the transmission failed completely with no warning or clear indication of what was wrong. The vehicle suddenly lost power while driving, creating a safety risk for me and my child. I was quoted around $12,000 for the transmission replacement initially before getting GM involved. GM covered all but approximately $3,600 out of pocket for me and also covered 100% of the timing cover replacement, which was found to be defective during the same repair. Now, at about 84,000 miles, the thermostat has failed, triggering the check engine light. This repair has not yet been completed and is estimated at around $1,500. My dealership informed me they keep thermostat parts in stock because this failure is so common on Acadias. There were no warning lamps or symptoms before any of these failures occurred. All repairs and diagnostics—including the current issue—were done at the same GMC dealership where I’ve always had my vehicle serviced on time. I’ve been a loyal customer and maintain my vehicle according to the recommended schedule. Despite that, I have faced repeated high-cost repairs on a 5-year-old vehicle with relatively low mileage, which has been financially and emotionally overwhelming—especially as a parent who recently lost employment. Having the transmission, timing cover, and now thermostat all fail in such a short time clearly raises concerns about the reliability, safety, and manufacturing quality of the 2020 GMC Acadia’s powertrain and engine systems. Given that GM has already covered most of the transmission and timing cover repairs and dealerships acknowledge frequent thermostat failures, this appears to be a systemic defect that warrants formal investigation.

Vehicle will shutter or buck at variable speeds like, 35-38 mph, 40-45 mph and so on. if I take my foot of the gas and reapply it will shutter buck again at almost any speed. I took it to a mechanic and there are no codes, no check engine light. Shop recommended changing the transmission fluid so we did. Car still responds the same way, shutters and bucks when reapplying fuel pedal or slow acceleration.

My 2020 GMC Acadia has experienced significant transmission issues, including [slipping / shuddering / “Service Transmission” warnings / loss of drive]. The problem has been diagnosed as a torque converter/transmission failure. GM has acknowledged known defects and issued recalls for 2019–2020 Acadia transmissions related to missing bolts in the start-stop accumulator endcap, which can cause fluid leaks and lead to torque converter/transmission failure. Many other owners have reported similar transmission issues, suggesting a systemic defect with the 9-speed transmission used in these vehicles. Despite these known issues, GM has declined to provide assistance with repairs. This failure compromises the safe operation of the vehicle, and I believe it warrants further investigation and potential recall.

Car keeps throwing Poo14 code for VVt sensor, I’ve replaced the sensors and checked wiring on the side of the road and no damage found, went online and read multiple complaints and recalls on the same issue I’m having with my car. I enter my vin and no recalls have been found. I have a 2020 gmc Acadia Denali 3.6l v6. As well and the rear view camera cutting in and out multiple times anlmost causing an wreck. and a system update didn’t fix the issue.

Valve body car would not go in park

The vehicle stalls when air start kicks on so when stopped auto stop kick on and when your ready to go the go stalls to turn back on. I have also lost power to the car randomly. Power train issue on car keeps coming on with engine light. I have taken to dealer when car was under warranty and they were very dismissive to my issue. They changed some sensor under warranty And they said the issue was fixed. But the issue remains and it’s causing several issues to the car with Also a fueling code to the engine light

Transmission Control Value issues. I was driving my car and RPM spiked up high and I coasted and there was no acceleration the rear wheel tires locked up and I felt a jerk. Placed the vehicle in park and pulled hand gear shifter into Drive and the vehicle shifted back into park by itself. Same thing happened on placing the vehicle in reverse. Like the car had a mindset of its own. Luckily I was only going 20 miles per hour this could have been a fatality. This vehicle is not on the recall list. It should be because they use all the same parts.

The contact owns a 2020 GMC Acadia. The contact stated while stopped at a traffic light and depressing the accelerator pedal after the light had changed, the vehicle hesitated and then lurched forward. The contact stated that an unknown warning light was illuminated. The contact stated that while driving at an undisclosed speed, the vehicle was vibrating abnormally. The vehicle was taken to an independent mechanic to be diagnosed and it was determined that the transmission needed to be replaced. The vehicle was not repaired. The manufacturer was informed of the failure. The contact researched online but found no recall related to the failure. The failure mileage was approximately 80,000.

Mileage: 80,000

The contact owns a 2020 GMC Acadia. The contact stated while driving from a complete stop and depressing the accelerator pedal, the vehicle hesitated to respond. The contact stated that the failure also occurred while driving at various speeds. Additionally, the contact stated that the vehicle experienced unintended downshifts while driving. The contact stated that the engine revved significantly without the accelerator pedal being depressed. The messages "Unable to Shift Gears" and "Service Vehicle” were displayed. The contact stated that the failure had been recurring while driving. The dealer was notified of the failure and an appointment was scheduled for diagnostic testing. The vehicle was not yet diagnosed or repaired. The contact related the failure to NHTSA Campaign Number: 20V668000 (Power Train); however, the VIN was not included. The manufacturer was not notified of the failure. The failure mileage was approximately 80,000.

Mileage: 80,000

The contact owns a 2020 GMC Acadia. The contact stated that while driving at various speeds, the vehicle was shuddering. No warning lights were illuminated. The vehicle was taken to a local dealer, where it was diagnosed that the torque converter needed to be replaced. The vehicle was repaired; however, the failure persisted. The contact stated that while starting the vehicle, and while driving at various speeds, a buzzing noise was heard coming from the engine compartment. The contact also stated that while driving at an undisclosed speed, the vehicle stalled with the anti-theft system warning light was illuminated and the vehicle lost motive power. The vehicle was able to be restarted; however, the contact stated that unknown alarm chimes were heard. Additionally, the liftgate opened independently and various other unknown warning lights illuminated, and messages were displayed. The contact stated that the vehicle lost motive power and failed to restart. The vehicle was towed back to the dealer however, the cause of the failure could not be duplicated. The vehicle was not repaired and remained at the dealer. The contact was made aware that the warranty had expired. The manufacturer was not made aware of the failure. The approximate failure mileage was 2,000.

Mileage: 2,000

15000 miles and already having transmission/torque converter shutter. In the shop now. Shutters in all gears and also while in cruise control at 70-75 + mph Dangerous when car won't shift.Dealer has confirmed this issue and has performed a flush. Problem still there and very noticeable. On star has reported these warnings and dealer confirmed codes.

I started receiving an error message that driver assist is reduced drive with car at 50k miles (i have an onstar diagnostic report and phone call made that day). It shut my car down and activated the parking break. I called Onstar at that moment it happened and they found nothing wrong with the car. It continued to happened several times after and each time I took it to the dealer they were unable to diagnose the problem. One time I was told there was a bulletin on it from GM, but not for the year of my car so they were not able to make the repair. When it finally started giving me the error all the time, they finally found it was the thermostat - $1600 and GM would not cover the part under warranty because I now had over the warranty miles even though it happened and was reported prior to that point. I have several people tell me with the same vehicle they too are having the problem - and it is costing each consumer $1600. GM knows it is a problem because it is all over the internet. There should be a recall and our costs reimbursed if we have had to make the repairs on our own.

After driving 5 miles up the road and 5 miles back home, I put the vehicle in park and it automatically went into neutral and the neutral button started flashing! Along with that I got an alert sent to my iphone (through the GMC app) and in the car saying “shift to park”. The car wouldn’t go into park! The vehicle hadn’t had any error codes or messages before this at all! It was out of nowhere! I drove it earlier that day and it didn’t do it! We also noticed after doing the update on July 7th, 2022 that the vehicle started shifting very hard! I was in the vehicle alone with 2 small babies and I couldn’t cut the vehicle off because it wouldn’t go into park! We had to wait for my husband to leave work and come home to unhook the battery just so we could get out of the car safely and so the battery wouldn’t go dead over night! The following morning we hooked the battery up and the vehicle wouldn’t turn over at all! We just bought this vehicle from a dealership in October 2021! We haven’t had it even a year yet and after researching our year make and model to see what was going on.. we have realized that almost every year from 2019 back had a recall concerning the “shift to park” error! I have been almost 2 weeks without a vehicle while it’s been at the Chevy dealership and it took 5 days for anyone to even contact me! It makes no sense and now they are saying that they can’t tell if it’s covered under my power train warranty because they can’t crank the vehicle to see if I’m within my 60k miles of the warranty! (Which I am.. my mileage is 47,204) This happened to my vehicle on 7-12-2022! I would love some feedback! I am glad I was home and not somewhere stranded with two babies on my own with this heat being so hot!! My email is [XXX] My phone number is [XXX] Thank you so much! I appreciate everything-needless to say I am not a big fan of GMC right now! [XXX] INFORMATION Redacted PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6).

AUTO STOP enabled while stopped at a stop sign on an uphill incline, there is enough of a delay on restart that it lurches and jerks upon restart, cant be good for transmission and passengers. very much a nusiance.

2020 GMC ACADIA. CONSUMER WRITES IN REGARDS TO LOSS OF POWER AT LOW SPEEDS AND JERKING WITH BRAKE LIGHT ILLUMINATED. *LD *JS

WHEN THE VEHICLE IS ALREADY IN MOTION, IT AUTOMATICALLY SHIFTS OUT OF DRIVE AND I AM LEFT IN THE MIDDLE OF THE ROAD UNABLE TO ACCELERATE FOR A FEW SECONDS UNTIL THE VEHICLE AUTOMATICALLY SHIFTS BACK TO DRIVE. THIS HAPPENS AFTER PULLING OUT OF MY GRAVEL DRIVEWAY WHICH IS A SLIGHT INCLINE, AND ONTO A HIGHWAY. THE CAUSE IS UNKNOWN. *TR

Mileage: 1,100