Subaru Subaru BOXER engines (EJ25, FB25, FA20, FA24) engines by year

By CarWhere Research · Updated

A Subaru BOXER engine is horizontally opposed: the pistons lie flat and face each other in a symmetrical side-to-side layout, so their forces cancel out. Subaru says this cuts vibration and lowers the center of gravity. Its US generations are the EJ25, the FB25 (2011–present), the FA20 (2013–2021) and the FA24 (2019–present).

Subaru introduced its first BOXER, a water-cooled aluminum four, in the Subaru 1000 on May 14, 1966. Subaru Corporation explains the name by the pistons' movement, which resembles a boxer's fists. In 2016 it said every vehicle it sold had a BOXER engine (excluding mini vehicles supplied by other makers in Japan) and that production had passed 16 million. Subaru adds that the engine's flat, low profile lowers the center of gravity and that the engine, mounted lengthwise in line with the drivetrain, is central to Symmetrical All-Wheel Drive.

The EJ25 was the 2.5L of the 1990s and 2000s: a SOHC non-turbo in mainstream models and a turbo through the 2021 WRX STI. The FB25 replaced it from 2011 with DOHC heads and chain-driven cams, and gained direct injection for 2019. The FA series began with the BRZ's 2.0L in 2013 and added the FA20 DIT turbo for the Forester XT and WRX. The 2.4L FA24 turbo has powered the Ascent, Outback XT, Legacy XT and WRX since 2019, and a non-turbo 2.4L powers the BRZ.

Subaru BOXER engines (EJ25, FB25, FA20, FA24) generations compared

Subaru BOXER engines (EJ25, FB25, FA20, FA24) generations: model years, peak Subaru-published output and documented problems
EngineModel yearsPeak hpPeak torque (lb-ft)Documented problemsRecalls
2.5L EJ25 BOXER (non-turbo and turbo)1996–2012 · 2004–202134133001
2.5L FB25 BOXER2011–2018 · 2019–present18217811
2.0L FA20 BOXER (BRZ) and FA20 DIT turbo2013–2020 · 2014–202126825802
2.4L FA24 BOXER (turbo and BRZ naturally aspirated)2019–present · 2022–present · 2022–present27127701

2.5L EJ25 BOXER (non-turbo and turbo)

The EJ25 is Subaru's earlier 2.5-liter BOXER four. Non-turbo versions powered Legacy, Outback, Forester and Impreza models from 1996 until the FB25 took over (2011–2013). Turbo EJ25s ran in the Forester XT, Legacy GT, Outback XT, WRX and WRX STI; the last, the STI, ended with the 2021 model at 310 hp.

2.5L EJ25 BOXER (non-turbo and turbo) specs, problems and recalls

2.5L FB25 BOXER

The FB25 is Subaru's 2,498 cc, DOHC 2.5-liter BOXER four, introduced in the 2011 Forester. It replaced the older EJ25 and powers the Forester, Outback, Legacy, Crosstrek and Impreza. Ratings rose from 170 hp to 182 hp with direct injection in 2019; Subaru rates 2025-on versions at 180 hp and 178 lb-ft.

2.5L FB25 BOXER specs, problems and recalls

2.0L FA20 BOXER (BRZ) and FA20 DIT turbo

The FA20 is Subaru's 2.0-liter FA-series BOXER four. A naturally aspirated version with a square 86 × 86 mm bore and stroke powered the 2013–2020 BRZ at 200–205 hp. The direct-injection turbo FA20 DIT made 250 hp in the 2014–2018 Forester 2.0XT and 268 hp in the 2015–2021 WRX.

2.0L FA20 BOXER (BRZ) and FA20 DIT turbo specs, problems and recalls

2.4L FA24 BOXER (turbo and BRZ naturally aspirated)

The FA24 is Subaru's 2,387 cc, 2.4-liter direct-injection turbo BOXER four. Subaru rates it at 260 hp and 277 lb-ft in the Ascent (2019–present), Outback XT (2020–present) and Legacy XT (2020–2025), and 271 hp and 258 lb-ft in the 2022-on WRX. The 2022-on BRZ uses a 228-hp naturally aspirated 2.4L.

2.4L FA24 BOXER (turbo and BRZ naturally aspirated) specs, problems and recalls

Related Subaru research

Confirm which Subaru BOXER engines (EJ25, FB25, FA20, FA24) a car was built with.

The engine and transmission are part of the factory build record for the VIN. The CarWhere Subaru build sheet reconstructs factory colors, options and packages from licensed VIN-level build data — availability is checked free, and it is $9.99 only when detailed build data is found for that VIN.

Subaru build sheet by VIN

Frequently asked questions

What is a Subaru boxer engine?

It is Subaru's horizontally opposed engine. The pistons face each other in a side-to-side symmetrical layout and move in opposition, which Subaru says cancels their inertia forces for low vibration and smooth running. The flat shape also sits low, lowering the car's center of gravity.

Why is it called a boxer engine?

Subaru Corporation says the name comes from the movement of the pistons, which resembles the movement of a boxer's fists.

Do all Subarus have boxer engines?

Every gasoline model in Subaru's current US lineup uses a BOXER engine. In 2016 Subaru Corporation said every vehicle it sold had one, excluding mini vehicles supplied by other makers in Japan. The electric Solterra has motors instead of an engine.

What is the difference between EJ, FB and FA engines?

The EJ25 is the older 2.5L, SOHC with belt-driven cams in non-turbo form. The FB25 (from 2011) is DOHC with chain-driven cams and is used in Subaru's mainstream models. The FA series (FA20 from 2013, FA24 from 2019) covers the BRZ and Subaru's turbocharged engines.

When did Subaru start making boxer engines?

Subaru's first BOXER engine went into the Subaru 1000 compact car in May 1966. Subaru Corporation reported 15 million BOXER engines built by February 2015.

Sources

Figures come from the individual engine pages, each of which cites Subaru-published ratings and NHTSA records as listed below.

  1. Subaru to Introduce All-New 2010 Legacy at New York International Auto Show (Mar. 30, 2009) — Subaru of America, Inc. (media.subaru.com)
  2. 2013 Subaru Legacy Debuts New Powertrain, EyeSight and Revised Styling (Aug. 2012) — Subaru of America, Inc. (media.subaru.com)
  3. EPA fuel economy: 1996 Subaru Legacy AWD (2.5L) — U.S. EPA / DOE (fueleconomy.gov)
  4. EPA fuel economy: 1998 Subaru Impreza AWD (2.5L) — U.S. EPA / DOE (fueleconomy.gov)
  5. Subaru Forester Gains New Infotainment Refinements for 2012 — Subaru of America, Inc. (media.subaru.com)
  6. EPA fuel economy: 1998 Subaru Forester AWD (2.5L) — U.S. EPA / DOE (fueleconomy.gov)
  7. EPA engine listings: 2010 Subaru Forester AWD — U.S. EPA / DOE (fueleconomy.gov)
  8. EPA engine listings: 2011 Subaru Impreza AWD — U.S. EPA / DOE (fueleconomy.gov)
  9. Subaru Announces Pricing on All-New 2010 Outback (Apr. 28, 2009) — Subaru of America, Inc. (media.subaru.com)
  10. EPA engine listings: 2012 Subaru Outback Wagon AWD — U.S. EPA / DOE (fueleconomy.gov)
  11. Subaru Announces Pricing on New 2010 Impreza (July 28, 2009) — Subaru of America, Inc. (media.subaru.com)
  12. Subaru Introduces 2011 Impreza WRX Models With New Wide-Body Designs (Mar. 21, 2010) — Subaru of America, Inc. (media.subaru.com)
  13. Subaru Announces Pricing for 2011 Impreza WRX and STI Models (July 22, 2010) — Subaru of America, Inc. (media.subaru.com)
  14. Subaru Announces Pricing for 2014 WRX and WRX STI (Aug. 6, 2013) — Subaru of America, Inc. (media.subaru.com)
  15. All-New 2015 Subaru WRX STI Debuts at North American International Auto Show (Jan. 13, 2014) — Subaru of America, Inc. (media.subaru.com)
  16. Subaru Tecnica International Unleashes Most Powerful Model Ever With Limited-Edition STI S209 — Subaru of America, Inc. (media.subaru.com)
  17. Subaru Announces Pricing for 2021 WRX and WRX STI Performance Cars (Dec. 10, 2020) — Subaru of America, Inc. (media.subaru.com)
  18. Fuji Heavy Industries news release on the WRX FA20 DIT Ward's 10 Best Engines award (Dec. 12, 2014) — Subaru Corporation (subaru.co.jp)
  19. EPA fuel economy: 2004 Subaru Forester AWD (2.5L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  20. EPA engine listings: 2021 Subaru WRX and WRX STI — U.S. EPA / DOE (fueleconomy.gov)
  21. EPA fuel economy: 2005 Subaru Legacy AWD (2.5L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  22. EPA fuel economy: 2005 Subaru Outback Wagon AWD (2.5L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  23. EPA fuel economy: 2008 Subaru Impreza AWD (2.5L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  24. EPA fuel economy: 2012 Subaru Legacy AWD (2.5L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  25. EPA engine listings: 2013 Subaru Forester AWD — U.S. EPA / DOE (fueleconomy.gov)
  26. EPA engine listings: 2014 Subaru Impreza AWD (incl. WRX and STI) — U.S. EPA / DOE (fueleconomy.gov)
  27. Subaru of America, Inc. Announces Pricing on 2011 Forester (Nov. 23, 2010) — Subaru of America, Inc. (media.subaru.com)
  28. EPA engine listings: 2004 Subaru Impreza AWD (incl. WRX and STI) — U.S. EPA / DOE (fueleconomy.gov)
  29. EPA engine listings: 2006 Subaru Impreza AWD (incl. WRX and STI) — U.S. EPA / DOE (fueleconomy.gov)
  30. EPA engine listings: 2013 Subaru Legacy AWD — U.S. EPA / DOE (fueleconomy.gov)
  31. Subaru Reveals All-New 2014 Forester Crossover SUV (Oct. 30, 2012) — Subaru of America, Inc. (media.subaru.com)
  32. Subaru Introduces All-New 2015 Outback at New York International Auto Show (Apr. 16, 2014) — Subaru of America, Inc. (media.subaru.com)
  33. Subaru Introduces All-New 2015 Legacy Sedan (Feb. 5, 2014) — Subaru of America, Inc. (media.subaru.com)
  34. 2013 Subaru Outback Debuts New Powertrain, EyeSight and Revised Styling (Aug. 2012) — Subaru of America, Inc. (media.subaru.com)
  35. Subaru Reaches 15 Million Production of Horizontally-Opposed "Boxer" Engines (Feb. 17, 2015) — Subaru Corporation (subaru.co.jp)
  36. 50th Anniversary of Subaru Horizontally-Opposed "Boxer" Engine (May 10, 2016) — Subaru Corporation (subaru.co.jp)
  37. Subaru Introduces All-New, U.S.-Built 2017 Impreza (2016) — Subaru of America, Inc. (media.subaru.com)
  38. Yaeger v. Subaru of America, No. 1:14-cv-04490 (D.N.J.), opinion granting final approval of oil-consumption settlement (Aug. 31, 2016) — U.S. District Court for the District of New Jersey (govinfo.gov)
  39. All-New 2019 Subaru Forester Debuts at New York International Auto Show (Mar. 28, 2018) — Subaru of America, Inc. (media.subaru.com)
  40. Subaru Debuts All-New Sixth-Generation 2020 Outback (Apr. 17, 2019) — Subaru of America, Inc. (media.subaru.com)
  41. 2021 Subaru Crosstrek Debuts with Refreshed Design, Suspension and an Available 2.5 Liter Engine (July 9, 2020) — Subaru of America, Inc. (media.subaru.com)
  42. Subaru Debuts the All-New 2024 Impreza Compact Car (Nov. 17, 2022) — Subaru of America, Inc. (media.subaru.com)
  43. Subaru Debuts All-New 2025 Forester SUV (Nov. 16, 2023) — Subaru of America, Inc. (media.subaru.com)
  44. Subaru Debuts All-New 2026 Outback with Bold New Styling, Upgraded Technology (Apr. 16, 2025) — Subaru of America, Inc. (media.subaru.com)
  45. Subaru Announces Pricing on 2027 Subaru Impreza — Subaru of America, Inc. (media.subaru.com)
  46. World Premiere of All-New 2019 Forester (US-spec specifications, Mar. 29, 2018) — Subaru Corporation (subaru.co.jp)
  47. World Premiere of All-New 2020 Subaru Outback (US-spec specifications, Apr. 18, 2019) — Subaru Corporation (subaru.co.jp)
  48. Subaru Introduces All-New 2025 Forester Hybrid with Next-Generation Hybrid Powertrain (Feb. 6, 2025) — Subaru of America, Inc. (media.subaru.com)
  49. Subaru Announces New 2026 Crosstrek Hybrid with Next-Generation Hybrid Powertrain (Jan. 16, 2025) — Subaru of America, Inc. (media.subaru.com)
  50. Subaru Debuts Next-Generation Hybrid System (Oct. 17, 2024) — Subaru Corporation (subaru.co.jp)
  51. EPA engine listings: 2019 Subaru Forester AWD — U.S. EPA / DOE (fueleconomy.gov)
  52. Subaru Announces Pricing on 2026 Crosstrek Including New 2026 Crosstrek Hybrid (July 16, 2025) — Subaru of America, Inc. (media.subaru.com)
  53. 2013 Subaru BRZ Marks Return of the Pure Sports Car (July 31, 2012) — Subaru of America, Inc. (media.subaru.com)
  54. 2017 Subaru BRZ Brings Higher Performance, Updated Styling and Series.Yellow Limited Edition (Oct. 24, 2016) — Subaru of America, Inc. (media.subaru.com)
  55. Subaru Announces Pricing on 2018 BRZ Sports Car (Dec. 1, 2017) — Subaru of America, Inc. (media.subaru.com)
  56. Subaru Announces Pricing on Updated 2017 BRZ (July 14, 2016) — Subaru of America, Inc. (media.subaru.com)
  57. EPA engine listings: 2020 Subaru BRZ — U.S. EPA / DOE (fueleconomy.gov)
  58. Subaru Introduces All-New 2014 Forester at Los Angeles Auto Show, full version (Nov. 27, 2012) — Subaru of America, Inc. (media.subaru.com)
  59. 2015 Subaru WRX Debuts New Level of Performance (Dec. 17, 2013) — Subaru of America, Inc. (media.subaru.com)
  60. EPA engine listings: 2018 Subaru Forester AWD — U.S. EPA / DOE (fueleconomy.gov)
  61. Subaru of America, Inc. Presents All-New 2019 Ascent 3-Row SUV — Subaru of America, Inc. (media.subaru.com)
  62. Subaru Storms Into Windy City with All-New Seventh-Generation 2020 Legacy (Feb. 7, 2019) — Subaru of America, Inc. (media.subaru.com)
  63. Subaru Announces Pricing on 2027 Ascent 3-Row SUV (June 11, 2026) — Subaru of America, Inc. (media.subaru.com)
  64. Subaru Debuts All-New Ascent 3-Row SUV (specifications, Nov. 29, 2017) — Subaru Corporation (subaru.co.jp)
  65. EPA fuel economy: 2027 Subaru Ascent (2.4L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  66. Subaru Debuts New 2022 Outback Wilderness (Mar. 30, 2021) — Subaru of America, Inc. (media.subaru.com)
  67. Subaru Announces Legacy Production Will End in 2025 (Apr. 23, 2024) — Subaru of America, Inc. (media.subaru.com)
  68. EPA fuel economy: 2025 Subaru Legacy AWD (2.4L turbo) — U.S. EPA / DOE (fueleconomy.gov)
  69. Subaru Debuts the All-New 2022 WRX (Sept. 10, 2021) — Subaru of America, Inc. (media.subaru.com)
  70. 2026 Subaru WRX Brings Back the Affordable Rally-Inspired Sports Sedan Starting at $32,495 MSRP (Jan. 20, 2026) — Subaru of America, Inc. (media.subaru.com)
  71. EPA fuel economy: 2022 Subaru WRX (2.4L turbo, 6-speed manual) — U.S. EPA / DOE (fueleconomy.gov)
  72. All-New 2022 Subaru BRZ Makes Global Debut (Nov. 18, 2020) — Subaru of America, Inc. (media.subaru.com)
  73. Subaru of America Announces Pricing on 2027 Subaru BRZ (June 4, 2026) — Subaru of America, Inc. (media.subaru.com)
  74. EPA fuel economy: 2027 Subaru BRZ (2.4L, 6-speed manual) — U.S. EPA / DOE (fueleconomy.gov)

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Independent reference compiled by CarWhere — not affiliated with or endorsed by Subaru of America, Inc. or Subaru Corporation. Subaru and the model names are trademarks of their owners.