2021 Subaru Forester Transmission Problems

While parking at low speed (around 4 MPH), your 2021 Subaru Forester suddenly accelerated on its own, drove out of the parking lot, and crashed into a wall. The airbags deployed, and then the vehicle shifted into reverse and crashed into a parked car before stopping. You and your three passengers were shaken but not seriously injured. The cause of the unexpected acceleration and reverse engagement has not been diagnosed, and no warning lights appeared before the incident.

Your car stalled unexpectedly while stopped at a red light in active traffic during rush hour. When you tried to move forward as the light changed, the Eyesight system disabled, the engine shut off, and the car refused to respond to gear changes or restart attempts until you completely powered it off and back on. The dealership performed a transmission control module (TCM) update and confirmed your battery is healthy, but could not replicate the problem or identify the root cause.

Your car's thermostat control valve failed, causing the engine to overheat in April 2025. After the overheating incident, the engine eventually failed at 65,000 miles, likely due to damage from that thermal event. The repair will involve replacing the thermostat control valve and potentially addressing any engine damage caused by the overheating.

At 40936 the valve body needed to be replaced. With such low milage vehicle is having problems.

Having repeat issues with the windshield cracking. My vehicle has around 32k miles, and I'm already on my 3rd windshield. I've never had this issue with any other vehicle. It's been extremely costly. Also the transmission failed and had to be replaced at 26,000 miles.

The 2021 Subaru Forester had been functioning normally with no warning lights. About 25 minutes into the drive I had come to a stop light on an upward incline. When the light turned green I moved from the brake to the gas as usual. However the auto-start function on the car failed, causing the engine to stall. A loud clunking sound was heard and the dashboard lit up with multiple lights, although I do no recall which ones were illumined. I attempted to press the gas again and the car did not respond. During this short time my foot was pressing on the gas the car rolled backwards and collided with the vehicle behind me. I continued attempting to press the gas pedal and still no acceleration was made. After parking and restarting the car it has resumed normal function. I have not yet visited the dealership so this issue has not yet been reproduced, nor has the offending system been inspected. I'm summary, the automatic engine start failed at a critical location, putting myself and others in serious danger and ultimately caused a crash.

Once or twice a day my vehicle hesitates from a light and I have to almost floor it to get it going again.I have brought it to 2 different Subaru dealers 3 times and they say they can't fix the problem.

Thermo control valve failed at about 42000 miles on 2021 Subaru Forester Premium, on 1/1/24. Owned 3 yrs 1 mo. Car was parked at work. Immediately after car was started up for return commute -- check engine light was on, ADAS systems ("Eyesight") disabled, blue low coolant temperature light on, and no heat through HVAC. Fortunately car driveable, despite safety being compromised with disabling of the safety features (blind spot monitor, rear cross traffic alert) and concern about damaging engine being forced to drive home with check engine light on. Engine failed to warm despite 40+ min highway trip. As this was commute vehicle, forced to take next day off work to have check engine light looked at. The next morning windshield ice had to be manually scraped (no heat). Drove car gingerly to dealership (<10 mins) avoiding freeways, for fear of damaging engine. Unknown if windshield defroster would've worked if started fogging mid-trip (safety concern). Dealership inspected vehicle - diagnosed thermo control valve failure, and replaced part. I was not charged as the car was still covered under powertrain warranty. No warning prior to the failure. Drove normally on the morning drive to work. Dealership replaced TCV with a part that has the same part number, per Subaru's TSB. Given experience of others indicating high failure rates of TCV after 3-4 years, and what I suspect is genuine design defect, I expect replacing the part to only have temporarily reset the clock -- seems certain to fail again. I have no confidence that Subaru has implemented an actual solution. I do not know if the next failure of this powertrain component will happen under warranty, or if it will incur signficant out of pocket costs (well over >$1000 to replace). Furthermore, if TCV fails whilst driving (as could have happened, and has been reported by others elsewhere), this will be a safety hazard with sudden disabling of blind spot monitor / rear cross traffic alert.

The contact owns a 2021 Subaru Forester. The contact stated while shifting the vehicle into the drive gear, the vehicle accelerated at high speed without any warning and drove into the wall of her garage causing front damage to the vehicle. The contact stated that the vehicle hesitated to turn off. No one was injured. The vehicle was not diagnosed. The dealer was not contacted. The manufacturer was not notified of the failure. The failure mileage was 8,000.

The contact owns a 2021 Subaru Forester. The contact stated while depressing the brake pedal and attempting to park in the driveway, the vehicle excessively independently accelerated in speed. The brake pedal failed to stop the vehicle and the vehicle was shifted into Park in order to come to a stop. The vehicle caused damage to the door and garage. There were no injuries reported. The vehicle was not diagnosed. The dealer was contacted, and they stated they were not aware of any recalls or complaints for the failure. The manufacturer was not contacted. The failure mileage was 10,000.

Car was parked on driveway (6 degree slope to rear) Car was placed in park Driver exited car to go into house when she came out car had rolled down the driveway to hit another car parked across street rear facing bot cars had rear damage. The same thing happened to the car one week later when parked in the garage placed in park but started to roll back. Was able to stop it because I was still in the car I use the parking brake now all the time

The vehicle gets a shudder at different speeds and it feels like it's either the transmission is slipping or its coming from the motor but it NEVER THROWS a Trouble Code so as the dealership says if its not throwing a trouble code they can't diagnose it until it does. So that's why I don't like these vehicles because no one know how to fix it old school by being a real mechanic and going old school to find the issue.