2021 Subaru Legacy Problems: 5 Known Issues
2021 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated November 2026
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2021 Subaru Legacy has 5 documented known issues, with 1 rated critical. The most serious is Thermo Control Valve Failure Causing Check Engine Light, Poor Heater Performance, and Possible Overheating ($1,200-$2,200 repair). Across all issues with published estimates, repair costs range from $250 to $2,200. DIY maintenance guides at au7o.io.
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All 5 Known Issues
When Issues Typically Appear
NHTSA Recalls8 recalls
POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)
Subaru of America, Inc. (Subaru) is recalling certain 2019-2020 Ascent, 2020 Legacy and Outback vehicles. A programming error in the Transmission Control Unit (TCU) may allow the clutch to engage before the drive chain is completely clamped.
BACK OVER PREVENTION:DISPLAY FUNCTION
Subaru of America, Inc. (Subaru) is recalling certain 2020 Legacy and Outback vehicles equipped with "high" grade and "mid" grade multimedia navigation. The August 2020 over-the-air software update may have timed out without completing the installation, corrupting the data, and causing the rearview display to shutoff intermittently. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 111, "Rear Visibility."
FUEL SYSTEM, GASOLINE:DELIVERY:FUEL PUMP
Subaru of America, Inc. (Subaru) is recalling certain 2019-2020 Ascent, 2018 Forester, 2018-2020 Impreza, Legacy, Outback, 2018-2019 BRZ, WRX, and Toyota 86 vehicles. The low-pressure fuel pump inside the fuel tank may fail.
SERVICE BRAKES, HYDRAULIC:PEDALS AND LINKAGES
Subaru of America, Inc. (Subaru) is recalling certain 2020 Outback and Legacy vehicles. The brake pedal mounting bracket may have a missing or insufficiently tightened bolt.
POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)
Subaru of America, Inc. (Subaru) is recalling certain 2020-2021 Outback and Legacy vehicles. A programming error in the Transmission Control Unit (TCU) may allow the clutch to engage before the drive chain is completely clamped.
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Frequently Asked Questions
What are the most common Subaru Legacy problems?
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2021 Subaru Legacy has 5 documented issues. Documented issues include: Thermo Control Valve Failure Causing Check Engine Light, Poor Heater Performance, and Possible Overheating, Windshield Cracking Easily and Eyesight Camera Recalibration After Glass Replacement, Transmission Inhibitor Switch Failure From Water Intrusion (NHTSA Recall 23V755000 / WRQ-23). Of these, 1 is rated critical and should be addressed promptly.
Is the Subaru Legacy reliable?
The 2021 Subaru Legacy has 5 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 1 issue is rated critical: Thermo Control Valve Failure Causing Check Engine Light, Poor Heater Performance, and Possible Overheating. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
How much does it cost to fix common Subaru Legacy problems?
Repair costs for known Subaru Legacy issues range from $0 to $2,200, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Thermo Control Valve Failure Causing Check Engine Light, Poor Heater Performance, and Possible Overheating, typically costs $1,200-$2,200 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 2020-2022 Subaru Legacy Thermo Control Valve Failure Causing Check Engine Light, Poor Heater Performance, and Possible Overheating?
Multiple owners of 7th-generation Legacy models have reported failure of the electronically controlled thermo control valve used in the FB25 cooling system. When the valve sticks or its internal position sensor fails, the car may illuminate the check engine light, lose cabin heat… Repairs typically run $1,200-$2,200. Severity: high.
What is the 2020-2024 Subaru Legacy Windshield Cracking Easily and Eyesight Camera Recalibration After Glass Replacement?
Owners of 2020-2024 Legacy models frequently report windshields that crack from small stone impacts or develop long cracks quickly, often near the camera area. Because the windshield is integrated with the EyeSight driver-assistance system, replacement is more expensive than conv… Repairs typically run $900-$1,800. Severity: medium.
What is the 2021-2023 Subaru Legacy Transmission Inhibitor Switch Failure From Water Intrusion (NHTSA Recall 23V755000 / WRQ-23)?
2021-2023 Legacy sedans are among the vehicles Subaru recalled under campaign WRQ-23. The defect is a weld on the park/neutral start interlock switch — the inhibitor switch — that was not made adequately, allowing water to enter the switch body and cause the switch to fail. A Leg… Severity: medium.
What is the 2021-2024 Subaru Legacy Infotainment Head Unit Freezing, Black Screen, and CarPlay/Android Auto Connectivity Problems?
The large center touchscreen used in the current Legacy has generated many owner complaints for lagging, freezing, random reboots, black screens, and unstable Apple CarPlay/Android Auto connections. In some cases climate and vehicle settings become difficult to access because man… Repairs typically run $0-$1,800. Severity: medium.
What is the 2021-2024 Subaru Legacy Battery Drain and No-Start from a Control Module Not Going to Sleep?
A well-documented issue on late-model Subaru vehicles including the Legacy involves parasitic battery drain tied to the Data Communication Module (DCM), telematics hardware, or related control modules not going to sleep properly. Owners report dead batteries after the vehicle sit… Repairs typically run $250-$1,200. Severity: medium.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.