This bulletin provides updated parts information and a service procedure to follow for removing accumulated carbon deposits from fuel injectors and internal engine components (e.g. intake valves and / or manifold, and combustion chambers). (This is an revised version of the original bulletin.)
full bulletin at NHTSA ↗2020 Subaru Forester engine problems
severe Owners of the 2020 Subaru Forester have filed 32 NHTSA complaints about the engine at roughly $3,100 to repair (U.S. federal records, as of July 2026). Source: NHTSA Office of Defects Investigation. See engine across all vehicles →
Complaints
32
Recalls
0
Avg fix
$3,100
| Model year | engine complaints |
|---|---|
| 2016 Forester | 32 |
| 2017 Forester | 23 |
| 2018 Forester | 14 |
| 2019 Forester | 60 |
| 2020 Forester (this page) | 32 |
| 2021 Forester | 15 |
| 2022 Forester | 4 |
| 2023 Forester | 4 |
1crash
2fires
What stands out
Owners have filed 32 engine 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 engine 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 provides updated parts information and a service procedure to follow for removing accumulated carbon deposits from fuel injectors and internal engine components (e.g. intake valves and / or manifold, and combustion chambers). (This is an revised version of the original bulletin.)
full bulletin at NHTSA ↗This bulletin provides updated parts information and a service procedure to follow for removing accumulated carbon deposits from fuel injectors and internal engine components (e.g. intake valves and / or manifold, and combustion chambers).
full bulletin at NHTSA ↗This bulletin announces the diagnostic procedures to be used when DTCs B1571(REFERENCE CODE INCOMPATIBILITY IMMOBILIZER CM TO ECM) and B1572(IMM CIRCUIT EXCEPT ANTENNA CIRCUIT) are detected by Keyless Access with Push Button Start(KACM).
full bulletin at NHTSA ↗This Bulletin provides the diagnostic procedure for the STARLINK® Remote Engine Start (RES).
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The dominant complaint in this cluster centers on the thermo control valve (Part 21319AA010), a component that Subaru redesigned in 2021 after acknowledging corrosion issues but assigned the same part number. Owners report that when this valve fails—typically between 13,000 and 76,000 miles—the check engine light comes on and *every* safety system shuts down permanently: EyeSight, Forward Collision Avoidance, lane assist, lane departure warning, adaptive cruise control, and automatic emergency braking. The engine temperature gauge reads cold, cabin heat stops working, and the vehicle often loses power or stalls. Diagnostic codes include P26A3, P26A5, P2682, and P0128.
Replacement costs range from $1,500 to $1,961, though many owners fall outside factory warranty coverage (60,000 miles). The critical issue: the replacement part has been on national backorder since at least March, with dealerships telling owners they have no arrival date and face multi-month waits. Some vehicles have sat on dealer lots for two months with no repair in sight.
Beyond the valve, owners report engine stalling without warning at traffic lights and highway speeds—sometimes tied to the auto start/stop fuel-saving feature that cannot be permanently disabled in this model year. Two owners describe post-collision fires that spread with alarming speed. One reports catastrophic crankshaft bearing failure without warning indicators, and another documents repeated unintended brake activation from throttle body failure that reoccurred after dealership repair.
Subaru has offered extended warranty coverage on the valve to some owners but only *after* failure occurs, and declined to issue a recall despite internal knowledge of the defect since early 2022.
Same Subaru Forester engine reports on nearby years: 2017 · 2018 · 2019 · 2021
Failure modes owners describe
Thermo Control Valve (Engine Coolant Bypass Valve) Failure
Defective thermo control valve (Part 21319AA010) causing engine temperature regulation failure, loss of cabin heat, and disabled safety systems. Part is known to corrode and fail prematurely; original part was redesigned with the same part number but faces chronic backorder status. When valve fails, all EyeSight and driver-assistance systems permanently disable until part is replaced.
When: Reported failures between 13,000 and 76,358 miles; failures occurring 1-4 years into vehicle ownership
Symptoms owners cite: Check engine light illuminated; Engine temperature gauge reads cold despite driving; Loss of cabin heat; heater blows cold air only; All EyeSight safety features disable (Forward Collision Avoidance, lane assist, lane departure warning, adaptive cruise control, lane keeping assistance, auto emergency braking); Vehicle loss of power and stalling at highway speed or traffic lights; Rough or choppy acceleration; Cruise control disabled; Vehicle sluggish or unresponsive to throttle input
Codes mentioned: P26A3, P26A5, P2682, P26A, P0128
Repairs/costs cited: Thermo control valve replacement cost ranges $1,500 to $1,961.51 at dealerships; some owners covered under factory warranty (first 60,000 miles), others under extended warranty, remainder out-of-pocket. Replacement part remains on national backorder as of late 2024 with dealerships reporting no estimated arrival date and multi-month wait times. Some owners report cooling gasket replacement also performed alongside valve replacement.
Recalls/TSBs owners mention: Subaru redesigned the part in 2021 but used same part number (21319AA010); new design installed on 2021 model year vehicles at factory. Extended warranty coverage provided to some owners but only after part failure occurs. No formal recall issued despite acknowledging defect. Subaru notified of issue in Feb 2022 service bulletin. Partial goodwill assistance offered in some cases but declined further escalation or full remedy in others. Parts cited as on backorder since March (year unspecified in narrative).
Post-Collision Fire—Fuel Shutoff System Failure
Vehicle experienced rapid uncontrolled fire following low-speed collision (deer strike at 60 mph, damage to front driver-side engine compartment). Fire breached firewall between engine and passenger compartment and engulfed entire vehicle in under 3 minutes. Allegation that fuel shutoff system (inertial fuel cutoff) designed to stop fuel flow after airbag deployment malfunctioned, allowing continued fuel flow and rapid flame spread.
When: Occurred at approximately 23,000 miles; vehicle was one year old and had been serviced by dealer one month prior
Symptoms owners cite: Fire started in front driver-side engine compartment following collision; Fire breached firewall in less than one minute; Rapid spread to entire vehicle within 3 minutes; No airbags deployed despite impact
Repairs/costs cited: Vehicle towed to insurance company's control; no dealership diagnosis or repair performed. Vehicle total loss.
Recalls/TSBs owners mention: Incident reported to Subaru of America. A similar complaint (2019 Subaru Forester fire after minor frontal collision) exists in NHTSA database.
Crankshaft Bearing Failure—Catastrophic Engine Damage
Engine unexpectedly stalled without warning while in traffic at low speed (15 mph), followed by complete catastrophic engine failure. Dealership diagnosis confirmed crankshaft bearing failure on cylinder 3; short block replacement and related engine component replacement (cam phasers, gaskets, seals) recommended. No warning lights or indicators appeared before, during, or after stall event.
When: Stall event occurred during driving; subsequent inspection revealed advanced bearing damage
Symptoms owners cite: Unexpected engine stall at 15 mph while in traffic; Complete loss of propulsion with no warning indicators; No check engine light, warning messages, or limp mode before, during, or after stall; Catastrophic engine failure following stall event
Repairs/costs cited: Dealership inspection confirmed diagnosis; short block replacement and related component replacement required.
Recalls/TSBs owners mention: Manufacturer notified through Subaru of America Customer Advocacy. Subaru offered partial goodwill assistance but declined further escalation or full remedy.
Throttle Body Malfunction with Unintended Braking Activation
Throttle body failure causing Forward Collision Avoidance Automatic Emergency Braking system to activate repeatedly without cause while driving at highway speed. Check engine and brake warning lights illuminated. Failure reoccurred after dealership repair.
When: Occurred at 35,600 miles
Symptoms owners cite: Forward Collision Avoidance Automatic Emergency Braking activated without driver input; Unintended brake application at 75 mph; Burnt smell in vehicle interior; Check engine light illuminated; Brake warning light illuminated; Failure became regular recurring occurrence
Repairs/costs cited: Dealership diagnosed and repaired throttle body; however, failure reoccurred after repair.
Recalls/TSBs owners mention: Manufacturer notified and case opened; no further details provided.
Auto Start/Stop Feature Engine Stalling at Idle
Auto start/stop fuel-saving feature causes engine to stall when vehicle is stopped in traffic at lights, stop signs, or during heavy stop-and-go driving. Engine stalls during restart sequence after the auto shutoff feature activates. Feature cannot be permanently disabled in this model year (unlike other Subaru models). Stalling creates safety hazard in traffic.
When: Occurs intermittently during normal stop-and-go driving
Symptoms owners cite: Engine stalls at traffic lights and stop signs; Engine stalls during auto start/stop cycle in stop-and-go traffic; Engine hesitates and shakes upon restart after auto shutoff; Vehicle unresponsive to accelerator input when restarting
Repairs/costs cited: One owner replaced battery at own cost after dealer initially blamed battery; stalling recurred with new battery. No permanent fix documented.
Recalls/TSBs owners mention: No manufacturer response documented in narratives.
Engine Loss of Power and Stalling at Highway Speed
Vehicle suddenly loses motive power and stalls while being driven at highway speed, leaving driver unable to accelerate or maintain speed. Can occur with check engine light illuminated or no warning lights at all.
When: Occurs at various mileages between 13,000 and 70 mph highway driving
Symptoms owners cite: Sudden loss of motive power at highway speed; Engine stalling while driving; Check engine light may or may not illuminate; Vehicle unresponsive to accelerator pedal input; Vehicle slows rapidly
Codes mentioned: P2682, P26A
Repairs/costs cited: Some cases traced to thermo control valve requiring replacement; one case involved cooling gasket and coolant control valve replacement.
Recalls/TSBs owners mention: In one case, manufacturer contacted and assisted with repair.
Synthesized from 32 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 1 most recent
While driving my 2020 Subaru Forester at approximately 15 mph, the engine unexpectedly shut off, resulting in an immediate loss of propulsion (vehicle stall while in motion). This created a safety risk because the vehicle was in traffic and could have been struck from behind or lost the ability to accelerate out of danger. No crash occurred and there were no injuries. There were no warning lamps,…
Had engine 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 engine problem on the 2020 Subaru Forester?
It's a meaningful issue. 32 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $3,100.
At what mileage does the engine typically fail?
Based on the 32 complaints filed, engine issues most often appear around 39,333 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 $3,100 for engine 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 engine?
No active recalls currently cover engine 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.