2021 Subaru Forester transmission problems

Filed Nov 1, 2026 · Electrical, Engine · TX

When coming to a stop, the auto start/stop system shuts the engine off and it fails to restart. All dashboard warning lights illuminate. The vehicle must be shifted to Park and restarted manually with the start button. The component that failed is the auto start/stop system; the exact cause is UNKNOWN. The vehicle is available for inspection upon request. This put safety at risk because the vehicle was left immobile in live traffic at stops until it could be restarted. There were no warning lamps or symptoms before the failure; the warning lights come on when the failure occurs. The vehicle was inspected by Gillman Subaru Southwest on October 229, 2026, and the dealer stated the battery performance was bad and in critical condition.

Filed Oct 28, 2026 · Transmission · 66,902 miles · GA

The contact owns a 2021 Subaru Forester. The contact stated that while driving and accelerating from a stop, the vehicle started bucking and hesitating. The vehicle was taken to the local dealer to be diagnosed, and it was determined that the transmission control valve body was inoperable and needed to be replaced. The transmission control valve body was replaced and the vehicle was repaired. The manufacturer was notified of the failure and informed the contact that the repair was not covered under an extended warranty associated with the failure. The failure mileage was 66,902.

Filed Oct 5, 2026 · Transmission · SC

The transmission very suddenly (perfectly fine one day, bad the next) developed a severe transmission slip. Like getting rear ended feeling transmission slip. Dealership quotes the CVT control valve body.

Filed Jul 2, 2026 · Electrical, Engine · WI

My 2021 Subaru Forester has a recurring, worsening defect in the Idle Stop/Start (ISS) system that creates a stalling hazard. When ISS shuts the engine off at a stop, the engine intermittently fails to restart when I try to move again. It cranks progressively slower, warning lights illuminate, a continuous alert sounds, and the vehicle cannot proceed until I shift to Park and restart manually. This has left me immobile in live traffic at lights, stop signs, and mid-turn. The system also attempts to shut down in unfavorable moments, such as mid-turn, or as I am already releasing the brake (meaning it was depressed only lightly or briefly); it then tries to restart while still mid-shutdown, producing a pronounced shake. This is not a battery-charge problem. It has occurred even when the battery tested above its rated cold-cranking amps, and after each failure the engine restarts smoothly by manual start, indicating the starter, engine, and fuel systems function normally. I raised this before 2024, but it was not recorded until May 2024. At that visit the dealer performed the TCM reprogramming in Service Bulletin 16-147-24 (Forester, auto start/stop engine speed drop on restart) plus an ECM update. A later visit added another ECM update. A dealer has now identified yet another TCM reprogramming, quoted for a fee. The failure has persisted across all of these updates. Dealer staff acknowledge repeated customer complaints with these exact symptoms and say there is no known effective fix. Because ISS cannot be permanently disabled through any factory control, I must remember to disable it manually every drive to avoid a restart failure in traffic. The vehicle is available for inspection. This is an ongoing, unresolved safety defect that repeated manufacturer software remedies have failed to correct, and it can leave the vehicle disabled in live traffic.

Filed Mar 12, 2026 · Engine, Transmission · 30,000 miles · IL · crash · 4 injuries

The contact owned a 2021 Subaru Forester. The contact stated that while driving at approximately 4 MPH and slowing to park, the vehicle accelerated on its own. The contact stated that the vehicle drove out of the parking lot and crashed into a wall. The contact stated that the air bags deployed and that the vehicle had then shifted into reverse (R) and driven out away from the wall and crashed into a parked vehicle and stopped. The contact stated she was unaware of any warning lights. The contact stated that she had 1 passenger in the front seat and 2 passengers in the rear seat. The contact stated that everyone was shaken and achy, but no cuts or other injuries. The contact stated later that the passengers went on their own to seek medical attention. The contact stated that the passenger front bumper, hood, and wheel well were damaged, and the rear bumper on the passenger side had damage from the crash with the parked vehicle. The contact stated that the other vehicle had minor damage to the right rear quarter panel. The police were called and issued a report. The vehicle was towed to a collision repair shop, but had not been repaired. The vehicle had not been diagnosed for the independent acceleration and reverse failures. The contact stated that her insurance provider had not yet declared the vehicle a total loss. The manufacturer was not informed of the failure. The failure mileage was approximately 30,000.

Filed Aug 13, 2025 · Transmission · MN

On 8/12/15, I had stopped at a stoplight. When the light changed and I attempted to move forward with traffic, the Eyesight Disabled warning came on and my car completely stalled and refused to move. The car prompted me to put it into park, I attempted this and it did not resolve the issue. After this, the car prompted to press the start/stop button. This also did not work. I eventually had to completely turn off the car while in an active lane of traffic and turn it back on. This resolved the issue. In less than 24 hours, I was at the dealership. They have been unable to determine what caused the vehicle to effectively shut off while idling. They are performing a TCM update and do not appear to believe the issue is a safety issue, however again the vehicle stalled in an active lane of traffic during rush hour. It felt like when the car goes into the gas saving mode while idling but this had not happened. It just stopped. This was an extremely unsafe situation to be in a car that can not move or have to try and get it into neutral and get it out of traffic on a busy road, moments after being on the highway. The dealership checked the battery twice and confirmed that it was functioning and I have the video walk through where the confirm the car is in good condition and they could not replicate the issue.

Filed Jul 20, 2025 · Transmission · MT

The Thermo Control Valve failed and the engine overheated in April 2025. The car has only been driven 1,200 miles since then and the engine failed at 65,000 miles likely due to the TCV failure and engine damage.

Filed Jan 3, 2025 · Engine, Transmission · NY

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

Filed Nov 17, 2024 · Transmission, Visibility · MI

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.

Filed Feb 12, 2024 · Acceleration, Engine · MA · crash

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.