The SUBARU EJ25D is a 2,457 cc, flat — four petrol engine produced between 2004 and 2012. It features a DOHC valvetrain, multi — point fuel injection, and aluminium cylinder heads with cast — iron block construction, delivering smooth power delivery for all — wheel — drive applications. In standard tune it produced 123 kW (167 PS) with 221 Nm of torque, forming part of Subaru's EJ engine family.
Fitted to models such as the Subaru Legacy, Outback, and Forester, the EJ25D was eng…
Subaru
All production years (2004–2012) meet Euro 4 emissions standards (VCA UK Type Approval #VCA/EMS/9243).
The SUBARU EJ25D is a 2,457 cc flat-four petrol engine engineered for all-wheel-drive mid-size vehicles (2004–2012). It combines DOHC architecture with electronic multi-point fuel injection to deliver refined everyday driving. Designed to meet Euro 4 standards, it represents a mature iteration of Subaru's horizontally-opposed engine platform.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,457 cc | |
Fuel type | Petrol | |
Configuration | Flat-4, DOHC, 16-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 99.5 mm × 79.0 mm | |
Power output | 123 kW (167 PS) @ 6,000 rpm | |
Torque | 221 Nm @ 3,600 rpm | |
Fuel system | Electronic multi-point injection | |
Emissions standard | Euro 4 | |
Compression ratio | 10.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Single-row roller chain (non-interference design) | |
Oil type | SAE 10W-30 (API SG) | |
Dry weight | 152 kg |
The SUBARU EJ25D was used across Subaru's BE/BH and BG/BH platforms with transverse mounting. This engine received platform-specific adaptations-shortened intake manifolds in the Legacy and revised cooling routing in the Outback-and from 2008 the facelifted Forester models adopted updated ECU calibration, creating minor software differences. All adaptations are documented in OEM technical bulletins.
The EJ25D's primary reliability risk is camshaft and lifter wear, with elevated incidence in sustained highway driving with frequent short trips. Internal Subaru quality reports from 2005 indicated a significant share of pre-2008 engines required camshaft replacement before 100,000 km, while NHTSA field reports show drivability faults contributing to emissions-related failures. Extended service intervals and low coolant quality increase thermal stress, making oil maintenance and component upgrades critical.
Analysis derived from Subaru technical bulletins (2004–2012) and NHTSA field reports (2005–2011). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The EJ25D offers dependable performance and good durability, but early models (2004–2007) had reliability concerns, particularly camshaft and lifter wear. Later revisions (post-2008) improved component durability, so well-maintained examples can exceed 150,000 km. Regular servicing with OEM-specified oil (10W-30) and timely lifter maintenance greatly enhance longevity.
The most frequent issues are camshaft and lifter wear, intake manifold gasket leaks, and water pump coolant leaks. These are well-documented in Subaru service bulletins. Lifter issues are linked to oil pressure and lubrication, while gasket problems stem from material aging under heat. Coolant leaks are design-related and affect pre-2008 units most.
This 2.5L petrol engine was used in Subaru's mid-size and utility cars under the SUBARU engineering designation. It powers the Legacy, Outback, and Forester variants. It is part of the EJ engine family and is designed for transverse applications. All applications meet Euro 4 emissions standards.
Limited tuning potential exists due to its naturally aspirated design and DOHC valvetrain. ECU remaps are not feasible due to analog control systems. Supporting modifications like intake/exhaust upgrades offer minimal returns. The engine is built for efficiency rather than performance, and stock internals are not designed for high boost. Most owners prioritize preservation over modifications.
Moderate for a utility engine. In a Legacy from 2005, combined consumption is ~8.8 L/100km (32.1 mpg UK). City driving may see 9.5–10.5 L/100km, while highway runs can achieve ~7.0 L/100km. Real-world figures depend heavily on driving style, as the engine rewards smooth inputs. Expect 30–34 mpg (UK) on mixed routes for a well-maintained EJ25D.
No. The EJ25D uses a non-interference timing chain design. This means if the chain skips or breaks, the pistons will not contact the valves, preventing catastrophic internal damage. However, any timing fault still requires immediate attention to avoid engine stalling and secondary issues. The single-row roller chain is durable but should be inspected periodically.
Specifies SAE 10W-30 API SG oil meeting Subaru specification. This formulation protects the hydraulic lifters and camshaft. Change intervals should not exceed 15,000 km or 6 months. Using incorrect oil can accelerate lifter wear and reduce engine lifespan. Always use high-quality petrol to support engine longevity.
Comprehensive technical documentation and regulatory references
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SUBARU Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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