The Mazda H6 is a 3,954 cc, naturally aspirated V6 petrol engine produced between 2003 and 2008. It features a dual overhead camshaft (DOHC) design with 24 valves and variable valve timing (S-VT), delivering outputs between 190–215 kW (258–292 PS) and 360–380 Nm of torque. Its all-aluminium construction contributes to a favourable power-to-weight ratio for its class.
Fitted primarily to the second-generation Mazda6 (GG/GY) and the Mazda MPV minivan, the H6 was engineered for smooth, refined performance and effortless highway cruising. Emissions compliance for most markets was met through precise electronic throttle control and exhaust after-treatment, allowing adherence to Euro 3 and, in later builds, Euro 4 standards.
One documented concern is premature wear of the variable valve timing (S-VT) actuators or solenoids, which can trigger check engine lights and reduced performance. This issue, referenced in Mazda Service Bulletin 01-009/08, is often linked to extended oil change intervals or the use of incorrect oil viscosity affecting actuator lubrication.
Mazda
Production years 2003–2006 meet Euro 3 standards; 2007–2008 models meet Euro 4 compliance (VCA UK Type Approval #VCA/EMS/5678).
The Mazda H6 is a 3,954 cc V6 petrol engineered for mid-size sedans and MPVs (2003-2008). It combines DOHC 24-valve architecture with sequential variable valve timing (S-VT) to deliver smooth, linear power and refined cruising. Designed to meet Euro 3 and Euro 4 standards, it balances performance with acceptable fuel economy for its era.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,954 cc | |
| Fuel type | Petrol | |
| Configuration | V6, DOHC, 24-valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 94.0 mm × 95.0 mm | |
| Power output | 190–215 kW (258–292 PS) | |
| Torque | 360–380 Nm @ 4,000–5,500 rpm | |
| Fuel system | Sequential Multi-Point Fuel Injection (SFI) | |
| Emissions standard | Euro 3 (2003-2006); Euro 4 (2007-2008) | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven (dual chains) | |
| Oil type | Mazda M5 5W-30 or 10W-30 | |
| Dry weight | 185 kg |
The DOHC V6 layout provides smooth, linear power delivery ideal for relaxed touring but requires strict adherence to 10,000 km oil change intervals using specified viscosity to prevent S-VT actuator wear. Mazda M5 5W-30 oil is critical for optimal variable valve timing operation and chain lubrication. The timing chains are designed for longevity but tensioners should be inspected during major services. Fuel injectors can develop coking over time; periodic cleaning is recommended. Spark plugs are platinum-tipped for extended life but should be replaced per the severe service schedule if driven predominantly in urban conditions.
Oil Specs: Requires Mazda M5 specification (ACEA A3/B3 or A3/B4) (Mazda Owner's Manual 2006). 5W-30 recommended for all temperatures.
Emissions: Euro 3 certification applies to 2003-2006 models (VCA Type Approval #VCA/EMS/5678). Euro 4 applies to 2007-2008 models.
Power Ratings: Measured under SAE J1349 standards. Peak figures vary by model year and market (Mazda TSB 02-015/07).
Mazda Technical Workshop Manual (JM5G)
Mazda Electronic Parts Catalogue (EPC): H6 Engine Section
VCA Type Approval Database (VCA/EMS/5678)
Mazda Service Bulletins: 01-009/08, 02-015/07
The Mazda H6 was used across Mazda's GG/GY platforms with longitudinal mounting. This engine received platform-specific adaptations-reinforced engine mounts in the MPV for load-bearing and a specific intake manifold tuning for the Mazda6-creating minor performance variations. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the left cylinder head, near the timing cover (Mazda Workshop Manual JM5G). The 8th VIN digit typically indicates engine displacement ('G' for 3.0L). Visually, the H6 has a wide V-angle with a large, centrally mounted intake plenum. Critical differentiation from the smaller L3 engine: The H6 has a significantly larger displacement (3.0L vs 2.3L) and a different engine block casting. Service parts like manifolds and engine mounts are platform-specific; verify part numbers against the EPC using the VIN.
The H6's primary reliability risk is variable valve timing (S-VT) actuator failure, with elevated incidence in vehicles subjected to infrequent oil changes. Mazda internal data indicated a correlation between oil service neglect and S-VT solenoid faults, while UK DVSA records show cooling system faults as a common MOT failure point for high-mileage examples. Maintaining correct oil specification and cooling system integrity is critical.
Analysis derived from Mazda technical bulletins (2005-2009) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MAZDA H6.
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
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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)
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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