This bulletin announces a design change made to the CVT Control Valve Body which incorporates an enhanced valve sleeve to improve durability. (This is an revised version of the orignal bulletin.)
full bulletin at NHTSA ↗2020 Subaru Forester powertrain problems
moderate Owners of the 2020 Subaru Forester have filed 28 NHTSA complaints about the powertrain at roughly $2,500 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See powertrain across all vehicles →
Complaints
28
Recalls
0
Avg fix
$2,500
| Model year | powertrain complaints |
|---|---|
| 2016 Forester | 43 |
| 2017 Forester | 42 |
| 2018 Forester | 18 |
| 2019 Forester | 38 |
| 2020 Forester (this page) | 28 |
| 2021 Forester | 13 |
| 2022 Forester | 4 |
1crash
What stands out
Owners have filed 28 powertrain complaints with NHTSA against this vehicle, but no formal recall covers the issue — the federal record reflects what manufacturers have admitted, not everything owners are reporting.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering powertrain on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This bulletin announces a design change made to the CVT Control Valve Body which incorporates an enhanced valve sleeve to improve durability.
full bulletin at NHTSA ↗In the interest of customer satisfaction, Subaru of America, Inc. (SOA) is extending the New Car Limited Powertrain Warranty coverage for the Continuously Variable Transmission (CVT) on the above listed models and model years from the original five (5) years or sixty thousand (60,000) miles (whichever comes first) to ten (10) years or one-hundred thousand (100,000) miles (whichever comes first).
full bulletin at NHTSA ↗This bulletin announces the service manual correction regarding clutch master cylinder reservoir service procedures.
full bulletin at NHTSA ↗This bulletin announces a design change made to the CVT Control Valve Body which enhancement was implemented to prevent abnormal operations. The updated valve body incorporates an enhanced valve sleeve to improve durability.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2020 Subaru Forester has a persistent thermo control valve (TCV) failure affecting the coolant bypass system. Owners report the valve fails within three years of ownership, often well before 60k miles, though some failures occur beyond that threshold. When it goes, the check engine light comes on and the entire EyeSight ADAS suite shuts down—collision detection, lane keep, blind spot warning, adaptive cruise, and emergency braking all go offline simultaneously, leaving drivers without critical safety nets.
The failure prevents the engine from regulating coolant temperature properly, leaving the engine running cool with no cabin heat or defrost. Subaru quietly redesigned the part and issued service bulletins to dealers, but refuses to recall it. Repair costs run $1500–$3000. The automaker covers it under a 60k-mile powertrain warranty, but owners over that mileage are stuck paying out of pocket for a defect Subaru knowingly created and then fixed in later model years.
Multiple owners report sudden loss of control, stalling on highways, and inability to accelerate during merges. One owner experienced a sudden stall while driving that forced a roadside pull-over and tow. Dealers acknowledge seeing the issue frequently but have not issued a recall despite the safety implications and widespread owner complaints.
Same Subaru Forester powertrain reports on nearby years: 2017 · 2018 · 2019 · 2021
Failure modes owners describe
Thermo Control Valve (TCV) / Engine Coolant Bypass Valve Failure
The thermo control valve malfunctions, preventing proper engine coolant regulation. Subaru redesigned this part and issued a service bulletin (TSB 09-80-21R, TSB-09-80-21, SB 16-132-20R) acknowledging the defect, yet has not issued a recall. Owners report failures primarily within 3 years regardless of mileage, though some occur beyond 60k miles. The failure triggers a check engine light and disables most safety systems.
When: Typically within 3 years; reported between 17k and 70k miles; one owner at 33,945 miles, another at 54,000 miles, another at 41k miles, another at 63k miles, and others at 51k and 62k miles
Symptoms owners cite: Check engine light illumination; Loss of heat/no cabin heat or defrost; Engine running cooler than normal or not reaching proper operating temperature; Coolant running at full (not regulating); Potential engine overheating risk; Cooling fans running too long at idle; Possible engine sludge formation due to lack of temperature regulation
Codes mentioned: P26A5 - Engine Coolant Bypass Valve A Position Sensor Circuit Range/Performance, P26A3 - Engine Coolant Bypass Valve A Control Circuit, P2A63 - Coolant Bypass Valve A Control Circuit Low
Repairs/costs cited: Replacement of thermo control valve assembly, sometimes with additional work (coolant bypass valve, intake gaskets, fuel line, coolant flush). Repair costs range from $1500–$3000+ per owner reports; typically covered under 60k mile powertrain warranty but not beyond
Recalls/TSBs owners mention: Subaru issued TSB 09-80-21R, TSB-09-80-21, and SB 16-132-20R acknowledging the defect and instructing dealers to replace the part with a redesigned version (sometimes carrying the same part number). Subaru covers the repair under the 60k mile powertrain warranty. Some owners report 'Goodwill' warranty extensions beyond 60k miles. No formal recall issued despite widespread complaints and Subaru's acknowledgment that the design was faulty.
Automatic Shutdown of Advanced Driver Assistance Systems (ADAS/EyeSight)
When the thermo control valve fails and the check engine light illuminates, the vehicle's entire ADAS system disables, including EyeSight camera, collision avoidance, lane keep assist, adaptive cruise control, blind spot warning, rear automatic braking, and ABS. This leaves the vehicle without critical active safety features despite passing diagnostic tests for other systems.
When: Upon check engine light activation due to TCV failure; reported across mileage range of 17k to 70k miles
Symptoms owners cite: All EyeSight and ADAS functions disabled simultaneously; Forward collision warning disabled; Automatic emergency braking disabled; Lane keep assist disabled; Blind spot monitoring disabled; Adaptive cruise control disabled; Lane departure warning disabled; Rear automatic braking disabled; ABS warning lights illuminated; Multiple warning lights on dashboard
Codes mentioned: Check engine light (linked to P26A5, P26A3, P2A63)
Repairs/costs cited: Safety systems restore upon replacement of the thermo control valve
Transmission Slippage and Surging / Acceleration Irregularities
Some owners report transmission slippage, bucking, surging, and inability to engage gears smoothly. One complaint references Subaru Service Bulletin 16-132-20R for transmission slippage during acceleration. Another reports the transmission unable to select the correct gear when climbing shallow hills. One narrative describes sudden unintended acceleration while at a stop, and another describes the vehicle refusing to engage reverse before suddenly lunging backward.
When: Reported early in ownership (500 miles, at purchase), and ongoing during operation; one complaint at hill climbing
Symptoms owners cite: Transmission slippage during acceleration; Bucking and surging sensation (strong enough to visually move occupants); Inability to select or engage gears smoothly; Reverse gear engagement delay followed by sudden lunge; Unpredictable transmission behavior in traffic; RPM inconsistencies in idle and reverse; Sudden unintended acceleration while stationary or at low speed; Loss of responsive acceleration
Codes mentioned: Sport mode indicator light blinking (reported in one case where TCV failed)
Repairs/costs cited: Dealers advised to observe and monitor; one complaint scheduled for manufacture inspection; another stated the vehicle 'performed as designed'
Recalls/TSBs owners mention: SB 16-132-20R referenced but specific recall or TSB action not detailed in narratives; one dealer told owner the behavior was normal ('performed as designed')
Loss of Vehicle Control and Dangerous Drivability Events
Multiple owners report sudden loss of vehicle control or dangerous driving conditions triggered by TCV failure, including sudden stalling on the highway, inability to accelerate during freeway merges, and loss of engine responsiveness. One owner stated the TCV failure caused 'dangerous loss of speed and control,' and another reported the vehicle stalling and stopping while driving on a road with the check engine light and multiple dash lights illuminating.
When: Reported across mileage range; stalling event on highway, merging event during freeway acceleration, unspecified timing for loss of responsiveness
Symptoms owners cite: Sudden stalling and loss of power while driving; Loss of acceleration during highway merge; Loss of speed and control on the road; Multiple warning lights and check engine light upon failure; Vehicle unable to restart after stalling; Engine light and temperature light activation upon driving over a small bump
Codes mentioned: Check engine light, Temperature warning light (blue thermometer icon)
Repairs/costs cited: TCV replacement required; one owner towed to dealership with $1800 repair cost (out of warranty); dealer advised against driving vehicle until repair
Synthesized from 28 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 0 most recent
Had powertrain trouble with your 2020 Subaru Forester?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the powertrain problem on the 2020 Subaru Forester?
It's a documented issue but not catastrophic. 28 complaints have been filed. Repairs average $2,500 and most owners catch it before it causes a breakdown.
At what mileage does the powertrain typically fail?
Based on the 28 complaints filed, powertrain issues most often appear around 7,500 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $2,500 for powertrain repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to powertrain?
No active recalls currently cover powertrain issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2020/Subaru/Forester.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.