Problems · by component
2020 Subaru Forester power train problems
32 owner complaints to NHTSA about the 2020 Subaru Forester cite power train, 5% of all 603 complaints for this model year.
Complaints
32
5% of all complaints
Crashes
1
Reported by owners
Fires
0
Reported by owners
Injuries
0
Reported by owners
What owners say about the power train
Verbatim from NHTSA complaints, newest first
“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.”
“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…”
“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.”
“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!”
“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.”
“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.”
Showing 6 of 32 reports. Read every report on NHTSA.gov.
Data from NHTSA Complaints API (owner reports, unverified) · synced Nov 3, 2026NHTSA vehicle page
Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.