2021 Subaru Forester electrical system problems

“I was stopped at a red light. When the light changed to green I put my foot on the gas and the car totally stalled out. There were no lights, fans or radio on just total silence. I tried to restart the car putting it is park and depressing the brake while pushing the start button and nothing. It didn't even try to turn over. silent, dead. I tried several times with no luck. I got out of the car to signal to the bus and row of cars behind me to pass me. I got back into the car and tried to start it again and this time it started. I drove immediately to the mechanic near my house. They couldn't see what was going on without me leaving the car next week. The battery had been replaced 6 months ago. This was a busy intersection and I was worried about getting out of the car but I had no choice.”

“The contact owns a 2021 Subaru Forester. The contact stated that while trying to roll up vehicle windows from driver sits and passenger sit they would roll up to 3/4th all the way up and they would roll back down after. The contact stated this was a recurring event. The dealer was aware of failure and diagnosed issue needing repairs for window regulator and run channels for driver and passengers side. Manufacturer was made aware of failure and let contact know it was outside of warranty. The failure mileage was approximately 22,500.”

“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…”

“Persistent Battery Drain on a 2021 Subaru Forester Limited. Problems began in year 4 of ownership (~17,000 mileage), after Subaru Starlink Subscription services expired. Red (Error) Starlink SOS indicator light was evident, where a normal light would show green. Battery would fully drain after about 3-4 days of inactivity while parked in a commercial garage. After repeated dead batteries, a jump-starter battery pack was used regularly, as well as a wall-outlet battery charger. The problem has not resolved with a new and appropriately specified AGM battery, replaced in December 2025. The only solution is to pull the engine-bay fuse #5, which disables the Data Communication Module (DCM), as well as other features (hands-free microphones and audio system). By pulling the fuse #5 consistently, the problem has ceased, even after a two-week period of no use. This provides irrefutable evidence that the DCM powered by fuse #5 is the source of the battery drain. The only resolution Subaru would offer was to insist on a dedicated diagnostic visit to a dealership, with the associated costs of hundreds of dollars to be borne by me, the customer, without a clear…”

“Driving along and various system warnings came on, then started losing power, then the engine died and the car was completely dead. Got a jump start and the car ran for a couple of minutes and died again. Had it towed to a repair shop and when they checked it the next morning, they couldn't find a problem and it ran great for them. I replaced the battery and alternator just to be safe because we were about to leave on a trip.”

“2021 Subaru Forester The vehicle has experienced recurring electrical and battery-related issues for several years. The original battery was replaced by the Subaru dealer with a larger-capacity battery because of repeated starting concerns. The replacement provided only temporary improvement. The vehicle continues to experience rough starting on a regular basis, even after installation of a newer aftermarket battery with a higher cold-cranking-amp rating. The current battery is approximately five months old. The most significant safety concern occurs during Auto Start-Stop operation. On multiple occasions, the engine has shut off at a stop as intended, but then failed to restart when attempting to move again. When this occurs, multiple warning lights illuminate on the dashboard and the vehicle is unable to proceed until it is shifted into Park and restarted manually. Because of this issue, I now disable the Auto Start-Stop feature on every drive to avoid a potential failure to restart while in traffic. The issue has been ongoing for years and has occurred with multiple batteries, including the dealer-installed replacement battery and a newer aftermarket…”