2021 Subaru Forester: engine stalls while driving

Filed Oct 25, 2026 · Electrical, Engine · RI

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.

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 Dec 5, 2025 · NJ

Vehicle was delivered with the wrong battery - reserve capacity. The car stalls out in idle position creating safety issues. My wife was stranded and we had the original battery replaced with the specs from the previous battery…causing the same issues to occur. Finally, we were informed of the improper battery installation

Filed Dec 4, 2025 · Driver assistance · FL

I am writing to file a formal complaint regarding repeated, severe, and dangerous malfunctions of the vehicle's engine Start/Stop (Idle Stop) feature. The system is failing to operate as intended, resulting in the engine stalling while the vehicle is in motion or under crucial driving circumstances, creating significant safety hazards. History of Incidents I have experienced four separate incidents where the engine unexpectedly stalled or shut down, creating extreme risk: Incident 1 (Railroad Tracks): The engine stopped while I was actively driving over railroad tracks. The car stalled on the tracks, and within seconds of the engine restarting, the crossing gates came down and a train passed. I narrowly avoided being hit by the train, missing the impact by approximately ten seconds. Incident 2 (Heavy Traffic/Bridge): During heavy, back-to-back traffic as a bridge (PGA bridge) was opening, the car momentarily stopped and then resumed movement. The unpredictable stopping motion created a severe risk of being rear-ended, as the following vehicle would have had difficulty anticipating the sudden, unintended stop. Incident 3 (December 2025): While taking a right turn, the engine stopped suddenly, with dash lights blinking, during only a slight pause in vehicle movement. This occurred while the vehicle was still maneuvering. Incident 4 (The following day): The engine stopping malfunction described in Incident 3 occurred again the next day. Attempted Repair and Ongoing Concern Two years ago, the dealership installed a new battery following the first two incidents. However, the problem has now recurred this week (December 2025). The dealership has informed me that using a third-party device to permanently disable the Start/Stop function would void the powertrain warranty. Causing Mechanical Stress: I believe the continuous, potentially faulty activation is putting unnecessary stress on the battery, electrical system, and engine components, which may ultimately shor

Filed Oct 24, 2025 · Engine · 32,000 miles · NJ

The contact owns a 2021 Subaru Forester. The contact stated that while stopped at a traffic signal, the vehicle stalled. No warning light was illuminated. The contact was able to restart the vehicle. The contact stated that on a separate occasion, while driving over railroad tracks, the vehicle stalled. No warning light was illuminated. The contact was able to restart the vehicle. The contact continued to drive, and two blocks later, the vehicle stalled. No warning light was illuminated. The contact was able to restart the vehicle. The vehicle was taken to the dealer, where it was diagnosed with battery failure. The battery was replaced. The contact picked up the vehicle, and on the drive back to the residence, the vehicle stalled. The contact stated that the vehicle was almost rear-ended by the vehicle behind. The vehicle was towed to the dealer. The dealer replaced the fuel injectors. The contact picked up the vehicle, and the following day, while driving to work, the vehicle jerked abnormally and the vehicle stalled. The vehicle was towed to the dealer; however, no cause for the failure was found. The vehicle was not repaired. The contact stated that the failure persisted. The manufacturer was not notified of the failure. The failure mileage was approximately 32,000.

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 Jun 27, 2025 · Electrical, Engine · CA

The Auto-Stop/Start feature frequently fails to properly restart the car, often causing the car to stall during the restarting process, leaving me effectively disabled on a busy road. The battery has already been replaced once.

Filed Jun 12, 2025 · Electrical · IA

My vehicle is equipped with automatic start/stop system. In early 2024, I began having issues with sluggish restart during the start/stop cycle. I took it into the dealer at that time, who stated it required a software update and charged the battery. The issue persisted. It was more serious, as it was not just sluggish on the restart, but the restart would fail and stall the car. This happened in heavy traffic, which was very scary and unsafe. I took the vehicle back into the dealer in late 2024 for the same issue. They did another software update and charged the battery again. They recommended that we purchase a new battery. One month later, we purchased an upgraded AGM battery, as it was recommended for auto start/stop systems. The issue continued to persist. First, with sluggish restart. Later, the auto start/stop system failed again in heavy traffic. We took the vehicle in again, and again the dealer stated it was the battery. They recommended we purchase a new battery. It was explained the battery was 6 months old, and the issue has never been fixed. Further, it was pointed out that the car could be restarted manually with the push button ignition, after a start/stop system failure. That led us to believe it was not a battery failure, but a deeper system failure. The dealer continues to assert it is the battery, even though it happened with a factory battery and a new, upgraded, battery. Neither of the batteries have failed testing, and report as "good" on the diagnosis forms. We believe there is a system issue, that is causing issues with the auto start/stop system, and is not being identified by the dealer. It is a safety issue, as it has happened in heavy traffic several times. We have attached diagnostic reports from March 2024 and June 2025, but cannot find the October 2024 diagnostic report.

Filed May 9, 2025 · FL

Automatic stop activated at traffic light. When the brake was disengaged, the star would not start. The occupant was stalled at the traffic light during rush hour in a thunderstorm with limited visibility for approximately 15 minutes. Winter Haven Police Department was dispatched but did not arrive probably due to other weather-related traffic situations. After that time, the engine did start and was moved into a lot without incident. The good Samaritan that assisted stated he had just stopped down the street on another disabled vehicle in traffic due to malfunctioning auto stop/start. Here is the issue. The alternator and battery have both been checked twice and were in proper order. The OE battery was in use. There was no warning to indicate any issue with the batter. In fact, the Subaru app was reporting the vehicle was operating normally while the vehicle was dead in the road. I work with a local law enforcement agency and have worked fatal crashes on that road. It is unacceptable for the vehicle to not have some type of redundant system to warn owners that the vehicle battery is failing before they are thrust into a possible deadly roadway breakdown.

Filed Jan 26, 2025 · NE

In the summer of 2024, my forester started completely stall out when I was stopped at a stop light. The auto start/stop system seemed to not turn back on. I would have to put the car in park, turn the car off and turn it back on. It was very scary being in traffic and people getting upset behind me. This happened multiple times. I took my car to the dealership. I was told an update needed to be installed and it was not anything I could do at home. After that point, it worked better, but still started back up hard at times. When I remembered, I typically started turning the feature off each time I drove it because I do not trust the feature. Unfortunately, it happened again yesterday. We were at a stoplight, and the car did not start back up, it stalled out. My husband had to quickly try to put the car in park, turn it off and then back on. Cars started honking at us. I am very concerned about this feature.

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.

Filed Jan 31, 2023 · Engine · NY

My vehicle stalls at stop signs and red lights at Least once or twice a day regularly I’ve taken to the dealer and they said I was the reason it does that but the car is barely 2 years old bought new it has been doing that since last year it needs to be fixed