The Honda K20A4 is a 1,998 cc, inline‑four naturally aspirated petrol engine produced between 2002 and 2006. It features a dual overhead camshaft (DOHC) 16‑valve layout with Honda's i-VTEC variable valve timing system. This configuration prioritizes a broad, flat torque curve and linear power delivery, producing a peak output of 155 PS.
Fitted primarily to the European‑spec Honda Accord (CL chassis) and Acura TSX (CL9), the K20A4 was engineered for refined, responsive performance in executive sedans. Emissions compliance for its production era was managed through precise fuel metering and a catalytic converter, meeting Euro 3 standards applicable to vehicles registered from January 2000 onwards.
One documented engineering focus was optimizing low-RPM torque for effortless drivability, addressed through specific camshaft profiles and intake manifold design as detailed in Honda Service Bulletin 03‑015. Later K20 variants, like the K20Z3, incorporated minor revisions to the cylinder head and ECU for enhanced emissions control.
Honda
Production years 2002–2006 meet Euro 3 standards for vehicles registered from January 2000 (VCA UK Type Approval #VCA/HON/02/01).
The Honda K20A4 is a 1,998 cc inline‑four naturally aspirated petrol engine engineered for mid-size sedans (2002-2006). It combines DOHC 16-valve architecture with i-VTEC variable valve timing to deliver a broad, accessible powerband. Designed to meet Euro 3 emissions standards, it balances responsive performance with everyday refinement.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,998 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, DOHC, 16‑valve (i-VTEC) | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 86.0 mm × 86.0 mm | |
| Power output | 155 PS (114 kW) @ 6,500 rpm | |
| Torque | 19.0 kgf·m (186 Nm) @ 4,000 rpm | |
| Fuel system | Honda PGM-FI (Programmed Fuel Injection) | |
| Emissions standard | Euro 3 | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven DOHC | |
| Oil type | 5W-30 API SL/SM (Semi-Synthetic/Full Synthetic) | |
| Dry weight | Not specified in primary sources |
The i-VTEC system provides a broad, flat torque curve ideal for relaxed cruising but requires meticulous maintenance of the VTEC solenoid and oil passages. Using the specified 5W-30 oil is critical for optimal lubrication and VTEC operation. The engine is sensitive to ignition timing; incorrect settings can lead to reduced power or increased emissions. The coil-on-plug ignition system is generally reliable but individual coils can fail. The timing chain is robust but the tensioner should be inspected during major services.
Oil Specs: Requires 5W-30 API SL/SM specification (Honda Owner's Manual CL/CL9). Modern equivalents meeting API SN/SP are acceptable.
Emissions: Certified to Euro 3 standards for vehicles registered from Jan 2000 (VCA Type Approval #VCA/HON/02/01).
Power Ratings: Measured under JIS D 1001 standards. Output figures are for the European-spec Accord variant (Honda Group PT-2005).
Honda Technical Information System (TIS): Workshop Manuals CL/CL9
Honda Electronic Parts Catalogue (EPC): Doc. H-K20A4-02
Honda Service Bulletin Database: SB 03-015
Japanese Industrial Standards: JIS D 1001 Engine Power Measurement
The Honda K20A4 was used across Honda's CL platform with transverse mounting and was not licensed to other manufacturers. This engine received minor platform-specific adaptations-primarily in accessory bracket positioning for the Accord versus the TSX-and no major facelift revisions occurred during its production run, ensuring good interchangeability within its model years. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the cylinder block, just below the exhaust manifold (Honda Workshop Manual CL/CL9). The 8th digit of the VIN for CL/CL9 chassis is 'K' for the K-series engine family. The K20A4 is visually identified by its black valve cover with "i-VTEC" cast into it and the lack of a balance shaft assembly (distinguishing it from the later K24A2). The intake manifold features a single, large plenum. Critical differentiator from K20Z3: The K20A4 uses a different ECU (P2T) and has a slightly different cylinder head casting. Service parts like the intake manifold are generally interchangeable, but cylinder heads and ECUs are not.
The K20A4's primary reliability consideration is maintaining the i-VTEC system, with neglect leading to solenoid failure and loss of high-RPM power. Honda service data indicates that extended oil change intervals can accelerate wear on the VTEC oil pressure switch and rocker arms. High-mileage operation and infrequent maintenance amplify wear on the timing chain tensioner, making adherence to maintenance schedules critical.
Analysis derived from Honda technical bulletins (2002-2007) and aggregated workshop repair data. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA K20A4.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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