The Honda K20A3 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 design with Honda's i-VTEC system engaging at 2,200 rpm for intake valves only and PGM‑FI fuel injection. This configuration prioritizes low-end torque and fuel efficiency while retaining high-RPM capability, making it ideal for sporty compact applications.
Fitted primarily to the seventh-generation (EP/ES) Honda Civic Si and Acura RSX for the North American market, the K20A3 was engineered to offer accessible performance with everyday refinement. Emissions compliance for its era was achieved through precise fuel metering and ignition control, meeting US EPA Tier 2 and California Air Resources Board (CARB) standards applicable to 2002–2006 model years.
One documented service consideration is the potential for i-VTEC solenoid screen clogging, which can prevent the system from engaging properly or trigger a ‘Check Engine’ light, as noted in Honda Service Bulletin 03‑045. This is typically caused by infrequent oil changes or using oil that doesn't meet specification. The engine was succeeded by the more powerful K20Z3 in 2007.
Honda
Production years 2002–2006 meet US EPA Tier 2 and CARB emissions standards for light-duty vehicles (EPA Engine Family K20A3.5HAX).
The Honda K20A3 is a 1,998 cc inline‑four naturally aspirated petrol engine engineered for sport compact applications (2002-2006). It combines DOHC i-VTEC architecture with PGM-FI electronic fuel injection to deliver a broad, usable powerband with strong low-end torque and a high-RPM crescendo. Designed to meet contemporary US emissions standards, it balances sporting character with daily-driver practicality.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,998 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | Inline‑4, DOHC, 16‑valve, i-VTEC (intake only) | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 86.0 mm × 86.0 mm | |
| Power output | 118 kW (160 PS) @ 6,500 rpm | |
| Torque | 190 Nm @ 4,000 rpm | |
| Fuel system | Honda PGM‑FI (Programmed Fuel Injection) | |
| Emissions standard | US EPA Tier 2 / CARB | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven DOHC | |
| Oil type | API SL 5W‑30 | |
| Dry weight | 132 kg |
The i-VTEC system provides strong low-RPM torque and smooth power delivery but requires strict adherence to 10,000 km oil change intervals to prevent solenoid screen clogging and ensure reliable engagement. Using the specified API SL 5W-30 oil is critical for protecting the VTEC mechanism. The chain-driven timing system is robust and maintenance-free for the life of the engine. The PGM-FI system demands a healthy battery for optimal sensor operation. i-VTEC solenoid screens are prone to clogging if oil changes are neglected, per Honda SIB 03-045.
Oil Specs: Requires API SL 5W-30 specification (Honda Owner's Manual). ACEA A5/B5 is an acceptable modern equivalent.
Emissions: Meets US EPA Tier 2 and CARB standards for 2002-2006 model years (EPA Engine Family K20A3.5HAX).
Power Ratings: Measured under SAE J1349 standards. Output is consistent across all model variants (Honda Workshop Manual).
Honda Technical Information System (TIS): Workshop Manual (2002), SIB 03-045
US Environmental Protection Agency (EPA) Engine Certification Database
Honda EPC (Electronic Parts Catalogue) Doc. H-K20A3-02
SAE International: J1349 Engine Power Certification Standards
The Honda K20A3 was used across Honda's EP/ES platforms with transverse mounting and was not licensed to other manufacturers. This engine received minor platform-specific adaptations-different intake manifolds and engine mounts between the Civic Si and RSX-but no major facelift revisions occurred during its production run, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, just below the cylinder head and behind the alternator (Honda Workshop Manual). The 8th VIN digit for K20A3-equipped EP3 Civics is typically 'K'. Visually, it features a black or silver valve cover with "i-VTEC" embossed on top. Critical differentiation from the K20A2: The K20A3 has a single camshaft position sensor on the exhaust side, while the K20A2 has sensors on both intake and exhaust cams. The engine harness connector for PGM-FI is unique to this engine family.
The K20A3's primary long-term concern is i-VTEC solenoid screen clogging, with elevated incidence in high-mileage or poorly maintained vehicles. Honda service data indicates this is often linked to neglected oil changes, while owner reports frequently cite secondary oil pump seal leaks. Aggressive driving and aftermarket exhausts without proper tuning can strain the ECU, making preventative maintenance critical.
Analysis derived from Honda technical bulletins (2002-2006) and aggregated owner workshop data (2003-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA K20A3.
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