2020 Subaru Forester transmission problems

Filed Sep 10, 2026 · Engine, Transmission · MI

Component/System Defect: Failed Thermo Control Valve (TCV) leading to sudden vehicle power loss / limp mode. Description of Safety Incident: While operating my vehicle at highway speeds late at night, the Thermo Control Valve (TCV) failed catastrophically without warning. The vehicle instantly experienced a massive loss of engine power and entered an aggressive "limp mode," causing a drastic, uncommanded deceleration in active traffic lanes.Due to the sudden reduction in speed and the low-visibility night conditions, a commercial semi-truck traveling directly behind my vehicle was nearly unable to brake in time and narrowly avoided rear-ending us. My family—including an elderly senior and a [XXX] child—was trapped inside the vehicle during this near-miss collision. The vehicle became an immediate hazard on a high-speed highway. The authorized dealership subsequently confirmed a failed Thermo Control Valve (TCV) and replaced the unit under Subaru's extended warranty program. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 19, 2026 · Electrical, Engine · CA

This 2020 Subaru Forester has experienced repeated failures involving the Auto Start/Stop system. When stopped in traffic, the system shuts the engine off as designed, but on multiple occasions the engine has failed to restart normally when the driver needed to proceed. This has left the vehicle unable to move in active traffic and created a serious risk of collision. The failures have occurred in highly dangerous situations, including a busy [XXX], a major [XXX] intersection, and most recently while entering a freeway. In these incidents, surrounding drivers had to brake hard to avoid striking the disabled vehicle. The occupants reasonably feared a serious collision, and the events were potentially life-threatening. The battery was replaced, but the Auto Start/Stop no-restart condition later occurred again, so battery replacement did not resolve the problem. Subaru issued Technical Service Bulletin 16-147-24 on XXX for 2019-2021 Foresters. The bulletin addresses TCM reprogramming related to engine behavior during Auto Start/Stop restart and instructs technicians to reprogram the TCM when the described symptom is reported. However, the bulletin’s warranty section provides reimbursement under the Basic New Car Limited Warranty. For a 2020 vehicle, the original 3-year/36,000-mile basic warranty would ordinarily have expired before this 2024 bulletin was issued. The vehicle is now being evaluated by an authorized Subaru dealer. The condition is intermittent and dangerous because the driver cannot know whether the engine will restart when movement is required. The vehicle is available for inspection. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 26, 2024 · Acceleration, Transmission · NC

Subaru of America is aware of the problem which impacts several models and model years, see Subaru Service Bulletin 16-132-20R. Transmission slippage and bounce feel during acceleration. Can be strong enough at times to visually see occupants moving with momentum/bounce at times. Could contribute to vehicle not maintaining/reducing/responding to speed control systems, failure of transmission components, stranding occupants, and other similar hazards that come with the mechanical failure of a transmission. Has caused slowing of acceleration which impacted surrounding traffic on a few occasions. Vehicle is scheduled to be inspected by manufacture dealership on morning of 08/27/24.

Filed Jun 13, 2024 · Acceleration, Transmission · NC

Check engine, forward collision warning, flashing "s"drive, no eyesight, automatic emergency braking warning lights, all came on at once and staying on. Possible thermo control valve issue - needs a recall!

Filed May 19, 2024 · Driver assistance, Engine · OH

2020 subaru forester just had a check engine light appear. The engine malfunction code is p26a3, which is a defective thermostatic control valve. This malfunction also affects the vehicle manufacturers advanced driver assitance systems such as: "eyesight" blind spot monitoring, lane keep assist, etc. Vehicle only has 51,000 miles on it.

Filed Apr 26, 2024 · Acceleration, Driver assistance · OH

While driving temperature light, check engine light, all ADAS lights came on as inoperable (cameras, warning, ABS, BSD/RCTA), no heat (including defrost) available to defrost or for cabin. Appointment 3/13 replaced thermo control valve assembly , coolant bypass valve, intake gaskets, fuel line, coolant, total charges $2070. Luckily had extended warranty I bought, that I had to make a claim on. Dangerous to drive (no camera based safety features available, no defrost for the snowy weather, no emergency braking or other collision safety features on, this affected the entire 'eyesight' system). The engine also had no thermo control regulation during this time, affecting not just then, but possible future performance and early aging due to disregulation.

Filed Apr 1, 2024 · Transmission · CA

I purchased a 2020 Subaru Forester in 2020. Last week, the Check Engine light came on and it was due to the thermo control valve that need replaced. My car was outside of warranty at 70k miles and Subaru’s customer advocacy office will not reimburse despite this being a faulty defect for many 2018-21 Foresters. There is a class action lawsuit filed but I’m still out $1900. There should be a recall and I should not be paying for this manufacturer defect.

Filed Mar 22, 2024 · Acceleration, Electrical · IL

The thermo control valve on vehicle failed on 2020 Subaru Forester which is causing vehicle to loose acceleration, multiple errors codes displaying on the vehicle instrument dash panel and no heat in the vehicle (see attached photo for reference). The failure of this device could cause a vehicle fire depending on what position/ and or state the thermo valve failed in. There needs to be a manufacturer recall on this particular part as there is numerous amounts of complaints and issues. Subaru needs to make it right with the customer. we need to drive safe vehicles on the road.

Filed Mar 20, 2024 · Transmission · WA

The thermo control valve failed causing the coolant to run at full and not allowing the engine to reach proper temperature and the heating system to not provide heat, also it caused multiple safety systems to turn off including eye sight, emergency braking, rear auto brake, lane keeping, adaptive cruise control, traction control. the failure of this unit is a known issue to Subaru per their own service bulletin 09-80-21, while mine was not covered by Subaru's own warranty due to the mileage this vehicle is less than 5 years old, the repair costs will be $2000.00+ as quoted by the dealer.

Filed Mar 20, 2024 · Transmission · NY

Thermo control sensor failed which will damage the motor if overheating dealer says it's going to cost me $1500 and it isn't covered under drivetrain warranty which is 5 years 60000 miles I have 27000 miles