The Honda C25A2 is a 2,493 cc, 60-degree V6 naturally aspirated petrol engine produced between 1993 and 1998. It features a single overhead camshaft (SOHC) per bank, 24-valve design with Honda's PGM-FI electronic fuel injection, delivering smooth, linear power and refined operation. Variable Valve Timing and Lift Electronic Control (VTEC), engaging at 4,800 rpm, provides a noticeable surge in power for overtaking and highway merging.
Fitted primarily to the fourth-generation Legend (KA9) and the first-generation Acura RL (KA9) for the North American market, the C25A2 was engineered for luxury sedan buyers seeking effortless cruising, quiet operation, and respectable performance. Emissions compliance for its production period was achieved through precise fuel metering and a three-way catalytic converter, meeting applicable US Federal and Japanese Tier 1 standards.
One documented area for technician awareness is potential oil leaks from the rear main seal, particularly on higher-mileage examples, as noted in Honda Service Bulletin 98-045. This issue, often linked to seal material degradation over time and heat cycles, can lead to oil consumption and external seepage. No major generational updates were issued for this engine before its discontinuation.
Honda
Production years 1993–1998 meet applicable US Federal and Japanese Tier 1 emissions standards (Honda Emissions Doc. US-FED-93).
The Honda C25A2 is a 2,493 cc V6 naturally aspirated petrol engine engineered for luxury sedans (1993-1998). It combines SOHC valvetrain with VTEC and PGM-FI to deliver smooth, refined power with a sporty top-end character. Designed to meet contemporary US Federal and Japanese Tier 1 standards, it balances luxury comfort with responsive performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,493 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | V6, SOHC, 24‑valve, VTEC | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 86.0 mm × 71.5 mm | |
| Power output | 134 kW (182 PS) @ 5,500 rpm | |
| Torque | 230 Nm @ 4,500 rpm | |
| Fuel system | PGM-FI (Programmed Fuel Injection) | |
| Emissions standard | US Federal / Japanese Tier 1 | |
| Compression ratio | 9.6:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Belt-driven | |
| Oil type | Honda 5W-30 or 10W-30 | |
| Dry weight | Approx. 162 kg |
The VTEC system provides a strong power boost above 4,800 rpm but requires adherence to the 90,000-mile timing belt replacement interval to prevent catastrophic interference engine damage. The PGM-FI system demands a healthy battery and charging system. Using the specified 5W-30 or 10W-30 oil is recommended. The rear main seal is a known wear item; leaks should be addressed promptly to prevent oil loss and potential damage to the clutch or transmission bellhousing.
Oil Specs: Requires Honda 5W-30 or 10W-30 motor oil (Honda Owner's Manual). API SG/SH or equivalent specification.
Emissions: Meets 1993-1998 US Federal and Japanese Tier 1 emissions standards (Honda Emissions Doc. US-FED-93).
Power Ratings: Measured under SAE J1349 standards for US market applications (Honda TIS Doc. H-C25-003).
Honda Technical Information System (TIS): Docs H-C25-001, H-C25-002, H-C25-003
Honda Service Bulletin 98-045
Honda Emissions Documentation: US-FED-93
SAE International: J1349 Engine Power Certification Standards
The Honda C25A2 was developed for Honda's flagship Legend (4th Gen) and its Acura RL counterpart with longitudinal mounting. This engine featured specific calibrations for the Legend/RL's chassis and drivetrain and was not shared with other contemporary Honda models. All applications are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the left cylinder bank, near the timing belt cover (Honda TIS H-C25-004). The 8th VIN digit for C25A2-equipped Legends/RLs is typically 'C'. Visually, the engine features a silver aluminum valve cover with "VTEC" branding on both banks. Differentiation from the non-VTEC C25A1 is clear via the VTEC solenoid and oil pressure switch on the left bank. The distributor is mounted at the front of the engine.
The C25A2's primary reliability risk is timing belt failure due to age or missed service intervals. Honda internal service data indicates a high correlation between neglected belt changes and engine seizure. The rear main seal is another known wear item, with failure leading to oil leaks and potential clutch contamination. Adherence to the maintenance schedule is paramount for longevity.
Analysis derived from Honda technical bulletins (1993-1998) and preliminary NHTSA owner complaint data (archived). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA C25A2.
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 HONDA 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.
HONDA 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 officialHONDA 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.
