2021 Subaru Forester — Known Issues & Recalls

Your engine suddenly lost all power while driving on the highway at 70 mph, forcing you to pull over into a dangerous shoulder area with traffic speeding past. A Texas Department of Transportation vehicle had to push your car about half a mile to safety. The dealer found that your Thermo Control Valve had failed, which they said is a common problem on this model. Subaru covered the repair under an extended warranty for this part, but you believe they should have replaced it proactively instead of waiting for it to fail.

Your 2021 Subaru Forester has stalled multiple times without warning lights appearing — first at a traffic light, then repeatedly while driving. The dealer replaced the battery and fuel injectors, but the stalling continued even after repairs, including an incident where the engine jerked abnormally before stalling. A dealer diagnostic couldn't identify the root cause. The fix may involve further electrical system diagnosis, fuel system testing, or engine control module evaluation to find why the engine is shutting off unexpectedly.

Your engine unexpectedly shuts down while your car is parked at traffic lights or stop signs, accompanied by a beeping sound. The dashboard may display an "Eyesight disabled" message, though this appears unrelated to the shutdown. This problem occurs intermittently and can't be reliably reproduced. The fix will likely involve diagnosing the engine control system and potentially updating or replacing components related to idle control or engine management.

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.

Your car was delivered with a battery that has the wrong reserve capacity, causing it to stall when idling—which creates a safety hazard. Even after replacing the battery with the original specs, the stalling continued until you discovered the battery wasn't installed properly. The fix will involve ensuring the correct battery is installed according to manufacturer specifications and verifying the installation is done correctly.

Your transmission shifted unexpectedly from Drive to Neutral twice in a single day after purchasing your 2021 Forester. The dealership was unable to reproduce the problem during diagnosis, and Subaru customer service suggested having another dealership inspect it since they couldn't confirm the issue. You're concerned about this potential safety hazard, especially for highway driving. Diagnosis and repair would likely involve a transmission fluid check, software update, or internal CVT transmission inspection by a qualified technician.

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 Forester's engine Start/Stop system is unexpectedly shutting down the engine while you're driving, including in dangerous situations like railroad crossings, heavy traffic, and turns. This has happened four times over two years despite a battery replacement two years ago, and it's recurring again. The repeated unexpected shutdowns put stress on your battery, electrical system, and engine, and fixing this will likely require dealership diagnostics and potentially replacement of the Start/Stop system components or engine control module.

Your Subaru's auto start/stop feature has shut off your engine completely while driving without warning, displaying an EyeSight error message and forcing you to restart. This happened twice — once during a left turn in traffic and once in stop-and-go conditions — creating dangerous situations where following drivers had no warning your car was stopping. The dealer replaced your battery but couldn't reproduce the problem, and Subaru has not provided a solution despite your safety concerns.

Your engine has shut down unexpectedly four times while sitting in traffic, requiring you to restart it manually—including one incident near a railroad crossing with your child in the car. You're also experiencing forward lurching at low speeds and hesitation when accelerating after stopping. These issues have continued even after service visits, and you believe they may be related to known problems with the Auto Start/Stop system and battery that Subaru has documented in technical service bulletins. Fixing this will likely involve software updates to the engine control system, battery diagnostics, or replacement of battery components.

Your 2021 Forester suddenly accelerated on its own twice within four days while you were stopped in parking lots, forcing you to slam on the brakes to avoid crashing. There were no warning lights or prior symptoms, and you've confirmed the floor mats weren't blocking the pedals. The dealer will need to diagnose the throttle control system, which may involve checking the electronic throttle body, accelerator pedal sensor, or engine control module.

Your lane-keeping assistance system failed to keep your vehicle on the road while driving on the highway, causing you to drift into a ditch. You were able to manually steer back, but you believe a deeper ditch could have caused a rollover. The problem appears to be that when your audio system is playing at normal volume, the warning chimes that alert you to take control aren't loud enough to hear over the music, so you don't get timely notice before the system disengages. This issue has happened multiple times over the past year.

While driving on a highway in New Jersey, your car suddenly lost all power, the steering locked up, and your dashboard lit up with warning lights and constant beeping. You were unable to exit the vehicle or steer it to safety, and a police officer had to push your car off the road. When the dealer performed a diagnostic test, they found no problems with your car, leaving the cause of this dangerous failure unexplained. The issue may require a comprehensive electrical system scan or engine control unit diagnostics to identify intermittent faults that standard tests might miss.

Your car caught fire shortly after you parked it at home. Before the fire, you noticed a low humming sound from the speakers and the car was slowing down on its own without you pressing the brake pedal. About 10 minutes after parking, smoke came from under the hood, followed by flames that engulfed the entire front of the vehicle. The fire was severe enough to melt the hood and damage a nearby tree. The cause has not been confirmed by Subaru or an independent mechanic, but given prior infotainment system issues and a warranty extension Subaru issued for known problems, an electrical failure may have ignited the fire.

Your Subaru's automatic emergency braking system suddenly activated and braked hard while you were driving on a clear, empty road with no obstacles present. This unexpected braking could have caused a rear-end collision with the vehicle behind you, creating a serious safety risk. The system may need recalibration or a software update to prevent false activation in normal driving conditions.

Your car's forward collision avoidance system is braking suddenly when there's nothing in front of you, which has almost caused other cars to rear-end you. Subaru says the EyeSight camera that controls this safety feature needs to be replaced, and they want you to pay for it. At only 4 years old with 38,000 miles, this seems like it shouldn't be failing yet.

Your car is draining its battery rapidly—you've already replaced the battery three times at 45,000 miles and been told you need another. The dealership says the start-stop system is the cause and recommends using a higher-capacity battery (750 CCA) than Subaru officially specifies. Additionally, your driver's seat adjusts itself to different positions on its own, and the car may stall while driving in traffic.

You heard a clunking noise from the front of your car starting at 37,000 miles. The dealer incorrectly diagnosed it as an ECU software issue and reprogrammed the system, but the noise continued. An independent mechanic found that both front control arm bushings were cracked and torn, allowing the control arm to move and create the clunking sound. Since control arm bushings are critical to steering control, their failure could have caused loss of vehicle control or an accident. The fix involves replacing the damaged control arm bushings.

Your car surges (jerks forward) during acceleration. The dealer found carbon buildup on the engine intake valves, which is causing poor fuel economy, higher emissions, and performance problems. The valves need professional cleaning to fix the issue, which costs around $300 and isn't mentioned in your scheduled maintenance guide. A professional fuel system or intake valve cleaning service will be required to remove the carbon deposits.