Automatic Transmission Control Module problems of the 2021 Subaru Forester

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.

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.