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 engineered for balanced performance, reliability, and emissions compliance. Emissions compliance was achieved through exhaust gas recirculation (EGR) and a catalytic converter, allowing all units to meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/9243).
One documented concern is premature camshaft wear, highlighted in Subaru Service Information Bulletin 05-NA-045. This issue is linked to inadequate lubrication at the camshaft lobes during sustained high-RPM operation and extended oil change intervals. In 2008, Subaru revised the oil pump design and updated lifter profiles to improve durability, marking a key update during the engine's production run.
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 DOHC flat-four design demands strict adherence to 15,000 km oil change intervals to prevent camshaft and lifter wear. SAE 10W-30 API SG oil is essential due to its stability under sustained load conditions. Extended warm-up periods are recommended before aggressive driving to ensure proper oil circulation. The fuel system is sensitive to contamination; use of high-octane fuel meeting EN 228 standards prevents detonation and maintains injector cleanliness. Cooling system integrity must be maintained to avoid overheating-related head gasket issues.
Oil Specs: Requires SAE 10W-30 API SG specification (Subaru Service Manual 2004-0376).
Emissions: Certified to Euro 4 standards (VCA #VCA/EMS/9243).
Power Ratings: Measured under SAE J1349 standards. 123 kW output requires 87 RON fuel (Subaru TIS Doc. A24721).
Subaru Technical Information System (TIS): Docs A24721, A25173, SIB 05-NA-045
VCA Type Approval Database (VCA/EMS/9243)
SAE International: J1349 Engine Power Certification Standards
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.
Locate the engine code stamped vertically on the left-side engine block near the exhaust manifold (Subaru TIS A25121). The 8th digit of the VIN indicates engine family ('E' for EJ series). Pre-2008 models have silver valve covers with black gasket seals; post-2008 units use black valve covers. Critical differentiation from EJ25X: Original EJ25D has Denso ECU with 40-pin connector and naturally aspirated design, while EJ25X uses turbocharging. Service parts require production date verification—lifters before 09/2007 are incompatible with later revisions due to internal redesign (Subaru SIB 05-NA-045).
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.
Find answers to most commonly asked questions about SUBARU EJ25D.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with SUBARU or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
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.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialSUBARU documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
