The Mazda S5Y5 is a 1,998 cc, inline — four petrol engine produced between 2004 and 2007. It features direct injection, variable valve timing (VVT), and a high compression ratio of 13.0:1, delivering responsive power and improved fuel efficiency. The cylinder head design enables efficient combustion for strong low — to — mid — range torque suitable for everyday driving.
Fitted to models such as the Mazda 3 (BM/BN), Mazda 6 (GJ/GK), and CX — 5 (BL/BM), the S5Y5 was engineered f…
Mazda
Production years 2004–2007 meet Euro 4 standards; no later emissions standard applies .
The Mazda S5Y5 is a 1,998 cc inline-four naturally aspirated petrol engine engineered for compact and mid-size models (2004-2007). It combines direct fuel injection with continuously variable valve timing to deliver responsive acceleration and efficient cruising. Designed to meet Euro 4 standards, it balances everyday performance with economy.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,998 cc | |
Fuel type | Petrol | |
Configuration | Inline-4, DOHC, 16-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 83.5 mm × 91.2 mm | |
Power output | 115–132 kW (156–180 PS) | |
Torque | 200–213 Nm @ 4,000 rpm | |
Fuel system | Direct Injection (DISI) | |
Emissions standard | Euro 4 | |
Compression ratio | 13.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Chain | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 145 kg |
The Mazda S5Y5 was used across Mazda's B-series platforms with transverse mounting and no licensed external usage. This engine received platform-specific adaptations—revised intake manifold geometry in the CX-5 and updated ECU calibration in the Mazda 6—and from 2006 the facelifted Mazda 3 adopted the upgraded S5Y5 variant with revised valve lift profiles, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from manufacturer technical service bulletins and industry workshop records. 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 S5Y5 delivers smooth power and good efficiency, but early models (2004–2006) are prone to intake valve carbon buildup, which can cause misfires and rough idle if neglected. Later revisions improved ECU strategies slightly, but carbon remains the primary concern. Regular induction cleaning every 40,000–60,000 km and strict use of Mazda Genuine 5W-30 oil greatly enhance longevity and performance.
The biggest issues are intake valve carbon buildup causing misfires, ignition coil failure under heat stress, throttle body carbon accumulation, and degraded PCV system components leading to oil leaks. These are well-documented in Mazda service bulletins, particularly SIB 07-007-18 for carbon management.
This 2.0L petrol engine was used across Mazda's core lineup from 2004–2007, appearing in the Mazda 3 (BM/BN), Mazda 6 (GJ/GK), and CX-5 (BL/BM), all badged as 2.0. It replaced the earlier S5Y4 and was succeeded by the newer PY-ZA. No other manufacturers used this specific engine variant.
Aftermarket ECU tuning is common on the S5Y5 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.
Excellent. In a Mazda 3 or CX-5, typical consumption is ~6.5 L/100km (city) and ~5.0 L/100km (highway), or about 56 mpg UK combined. Real-world figures depend on driving style, but expect 50–60 mpg (UK) on mixed roads for a healthy S5Y5 with clean intake valves and proper maintenance.
Yes. The S5Y5 is an interference engine. If the timing chain fails or jumps, pistons can strike open valves, resulting in severe internal damage. While chain failure is rare under maintenance, any unusual noise from the timing area demands immediate inspection.
Mazda specifies Mazda Genuine 5W-30 synthetic oil meeting API SL or ILSAC GF-3 standards. Always use this exact spec and change it every 10,000 km or annually to minimize carbon formation and ensure optimal lubrication of the high-pressure valve train.
Comprehensive technical documentation and regulatory references
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Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
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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