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 ↗2021 Subaru Forester powertrain problems
severe Owners of the 2021 Subaru Forester have filed 13 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
13
Recalls
0
Avg fix
$2,500
| Model year | powertrain complaints |
|---|---|
| 2017 Forester | 42 |
| 2018 Forester | 18 |
| 2019 Forester | 38 |
| 2020 Forester | 28 |
| 2021 Forester (this page) | 13 |
| 2022 Forester | 4 |
| 2025 Forester | 3 |
5crashes
4injuries
When does it fail?
Of the 13 powertrain complaints filed for the 2021 Subaru Forester, here's the actual mileage breakdown — failures cluster heaviest at 0-25,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
No new NHTSA powertrain complaint has been filed on this vehicle in over 3 years — the issue may be aging out of the active population.
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 ↗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 ↗This bulletin outlines the repair procedure to follow when the axle nut has rotated from its originally torqued position.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Owners report the thermo control valve failing around 40,000 miles, disabling Eyesight safety features and HVAC heat while triggering a check engine light. Subaru replaces it under warranty with the same part number per TSB, but owners are skeptical the fix is permanent and expect $1,000+ repair costs after warranty expires.
Multiple owners describe unintended acceleration incidents at very low mileage—as early as 8,000 miles. Vehicle accelerates without pedal input while parking or at traffic lights, brakes don't stop it, and collisions result. One vehicle also shifted to reverse on its own. Dealerships haven't diagnosed these.
Transmission problems are widespread: one owner's transmission failed at 26,000 miles and required replacement; another needed a valve body replacement at 40,936 miles. A separate owner reports hesitation from stops at traffic lights occurring daily, but multiple dealership visits turned up nothing because no trouble code appears.
Two owners describe complete vehicle stalls—one at a traffic light during rush hour with the Eyesight system disabled, another at a stoplight on an incline where the auto-start function failed and the car rolled backward into the vehicle behind it. In the first case, dealership performed a TCM update but couldn't replicate or resolve the issue. One owner also reports the vehicle rolling backward out of Park on a driveway, twice.
A separate complaint mentions transmission shuddering at various speeds without generating any diagnostic codes, leaving dealerships unable to help.
Same Subaru Forester powertrain reports on nearby years: 2018 · 2019 · 2020
Failure modes owners describe
Thermo Control Valve (TCV) Failure
Thermo control valve fails, causing loss of engine heat, disabled HVAC, disabled Eyesight safety systems (blind spot monitor, rear cross traffic alert), and check engine light. Owners report high failure rates and suspect a design defect. Subaru replaces the valve under powertrain warranty with same part number per TSB, but owners doubt the fix is permanent.
When: 42,000 miles; also reported at 65,000 miles after initial failure at lower mileage
Symptoms owners cite: Check engine light illuminates; Eyesight safety systems disabled; Blue low coolant temperature light; No heat through HVAC system; Engine fails to warm up during extended driving; Loss of blind spot monitor and rear cross traffic alert
Repairs/costs cited: Dealership replaced TCV with same part number per Subaru TSB; covered under powertrain warranty. Owner reports replacement cost would exceed $1,000 if out of warranty.
Recalls/TSBs owners mention: Subaru TSB on file for TCV replacement using same part number; Subaru powertrain warranty covers initial failure in complaint #1
Unintended Acceleration
Vehicle accelerates on its own during low-speed parking or at traffic lights, without driver input. Multiple incidents result in collisions. Owners report no warning lights or ability to stop with brakes. In one case, vehicle also shifted into reverse on its own after initial crash. Root cause not diagnosed in any complaint.
When: 8,000 to 30,000 miles
Symptoms owners cite: Vehicle accelerates without driver pressing accelerator pedal; Occurs while parking or at low speeds; Brake pedal fails to stop acceleration; Vehicle shifts into reverse without driver input (one incident); No warning lights prior to failure; Results in collisions with walls and other vehicles
Repairs/costs cited: Vehicles not diagnosed; some not taken to dealership. No repairs documented.
Transmission Hesitation / Hard Start from Stop
Vehicle hesitates or fails to accelerate smoothly when moving from a stop, particularly at traffic lights. Owner reports symptom occurs once or twice daily and requires heavy throttle input to resolve. Multiple dealership visits have not identified or corrected the problem.
When: Unclear specific mileage; occurs during normal driving
Symptoms owners cite: Hesitation from a stopped position at traffic lights; Requires pressing accelerator pedal harder than normal to move forward; Occurs once or twice per day; No trouble codes generated
Repairs/costs cited: Owner visited 2 different Subaru dealers 3 times; dealers unable to diagnose or repair due to lack of trouble codes
Eyesight System Stall / Complete Vehicle Shutdown
Vehicle stalls completely while idling in traffic, with Eyesight system disabled warning. Engine will not respond to start/stop button or accelerator input. Owner must fully power down vehicle in active traffic lane and restart. Dealership performs TCM update but cannot determine root cause.
When: At stoplight during rush hour; mileage not stated
Symptoms owners cite: Eyesight Disabled warning illuminates; Vehicle stalls and refuses to move while in active traffic lane; Vehicle does not respond to start/stop button; Engine unresponsive to driver input; Vehicle must be completely powered down and restarted to recover
Repairs/costs cited: Dealership performed TCM (transmission control module) update; battery confirmed functional; issue could not be replicated
Recalls/TSBs owners mention: Dealership performed TCM software update
Automatic Engine Start Function Failure
Auto-start / stop function fails to activate engine when moving from stopped position at traffic light on incline. Engine stalls with loud clunking sound and multiple dashboard warning lights. Vehicle does not accelerate and rolls backward into following vehicle.
When: During normal driving at traffic light; mileage not stated
Symptoms owners cite: Auto-start function fails at traffic light; Engine stalls; Loud clunking sound from engine; Multiple dashboard warning lights (owner cannot recall which); Vehicle unresponsive to accelerator pedal; Vehicle rolls backward after stall
Repairs/costs cited: Vehicle not yet inspected at dealership; issue has not been reproduced
Park Gear Failure / Vehicle Rolling
Vehicle does not hold in Park position and rolls backward on slope or driveway. Occurs when parked in Park gear without parking brake engaged. Vehicle rolls down driveway and into parked vehicles on two separate occasions.
When: Low mileage; occurs during parking on incline
Symptoms owners cite: Vehicle rolls backward while in Park gear; Occurs on driveway with downward slope; Vehicle does not hold stationary when unattended; Repeated failures on separate occasions one week apart
Repairs/costs cited: Owner now uses parking brake routinely to prevent further incidents; no dealership diagnosis documented
Transmission Shudder / Slipping (Undiagnosed)
Vehicle shudders at various speeds; owner suspects transmission slipping or motor issue. No trouble codes are generated, so dealership states they cannot diagnose until a code appears. Problem persists without resolution.
When: Mileage not stated
Symptoms owners cite: Shuddering sensation at different speeds; Feels like transmission slipping or motor issue; No trouble codes generated
Repairs/costs cited: Dealership states they cannot diagnose without a trouble code; issue remains unresolved
Transmission Failure
Transmission completely failed and required replacement. Low mileage vehicle; owner also reports repeat windshield cracking issues (3 windshields by 32k miles).
When: 26,000 miles
Symptoms owners cite: Transmission failure requiring replacement
Repairs/costs cited: Transmission replaced at 26,000 miles
Valve Body Failure
Valve body (transmission component) required replacement at very low mileage, indicating premature wear or manufacturing defect.
When: 40,936 miles
Symptoms owners cite: Valve body failure
Repairs/costs cited: Valve body replaced
Synthesized from 13 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 2 most recent
The contact owns a 2021 Subaru Forester. The contact stated while shifting the vehicle into the drive gear, the vehicle accelerated at high speed without any warning and drove into the wall of her garage causing front damage to the vehicle. The contact stated that the vehicle hesitated to turn off. No one was injured. The vehicle was not diagnosed. The dealer was not contacted. The manufacturer…
The contact owns a 2021 Subaru Forester. The contact stated while depressing the brake pedal and attempting to park in the driveway, the vehicle excessively independently accelerated in speed. The brake pedal failed to stop the vehicle and the vehicle was shifted into Park in order to come to a stop. The vehicle caused damage to the door and garage. There were no injuries reported. The vehicle…
Had powertrain trouble with your 2021 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 2021 Subaru Forester?
It's a meaningful issue. 13 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $2,500.
At what mileage does the powertrain typically fail?
Based on the 13 complaints filed, powertrain issues most often appear around 16,000 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/2021/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.