The Mazda JJM is a 2,488 cc, naturally aspirated inline‑four petrol engine produced between 2014 and 2020. It features a dual overhead camshaft (DOHC) design with 16 valves and Mazda's Skyactiv-G technology, including a high 13.0:1 compression ratio and 4-2-1 exhaust manifold. Standard output is 138 kW (188 PS) and 250 Nm of torque, prioritising efficiency without sacrificing drivability.
Fitted to the third-generation Mazda6 (GJ) and the CX-5 crossover, the JJM was engineered for responsive, linear power delivery and excellent fuel economy. Emissions compliance for European markets was met through precise direct injection and exhaust after-treatment, allowing adherence to Euro 5 and, in later builds, Euro 6 standards.
One documented concern is carbon buildup on the intake valves, a known characteristic of direct injection engines. This issue, referenced in Mazda Service Bulletin 03-012/16, can lead to rough idle or hesitation if not addressed. Mazda recommends periodic intake cleaning as part of severe service maintenance.
Mazda
Production years 2014–2015 meet Euro 5 standards; 2016–2020 models meet Euro 6 compliance (VCA UK Type Approval #VCA/EMS/9876).
The Mazda JJM is a 2,488 cc inline‑four petrol engineered for mid-size sedans and crossovers (2014-2020). It combines DOHC 16-valve architecture with Skyactiv-G direct injection to deliver responsive, linear power and class-leading fuel efficiency. Designed to meet Euro 5 and Euro 6 standards, it balances performance with low emissions.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,488 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 89.0 mm × 100.0 mm | |
| Power output | 138 kW (188 PS) | |
| Torque | 250 Nm @ 4,000 rpm | |
| Fuel system | Direct Injection (Skyactiv-G) | |
| Emissions standard | Euro 5 (2014-2015); Euro 6 (2016-2020) | |
| Compression ratio | 13.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven | |
| Oil type | Mazda M5 0W-20 or 5W-30 | |
| Dry weight | 125 kg |
The high-compression Skyactiv-G design provides excellent fuel efficiency and linear power but is susceptible to intake valve carbon buildup due to its direct injection system. Mazda M5 0W-20 oil is recommended for optimal fuel economy and chain lubrication. The timing chain is designed for the engine's life but should be inspected if unusual noise is present. Periodic intake valve cleaning is advised, especially for vehicles driven predominantly in short-trip urban conditions, to maintain smooth idle and throttle response.
Oil Specs: Requires Mazda M5 specification (ACEA C2 or C3) (Mazda Owner's Manual 2017). 0W-20 is preferred for fuel economy; 5W-30 is acceptable for all temperatures.
Emissions: Euro 5 certification applies to 2014-2015 models (VCA Type Approval #VCA/EMS/9876). Euro 6 applies to 2016-2020 models.
Power Ratings: Measured under SAE J1349 standards. Output is consistent across model years and markets (Mazda TSB 04-018/17).
Mazda Technical Workshop Manual (GJ5G)
Mazda Electronic Parts Catalogue (EPC): JJM Engine Section
VCA Type Approval Database (VCA/EMS/9876)
Mazda Service Bulletins: 03-012/16, 04-018/17
The Mazda JJM was used across Mazda's GJ platforms with transverse mounting. This engine received platform-specific adaptations-different engine mounts for the CX-5 to accommodate AWD hardware and a specific exhaust 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 engine block, near the alternator (Mazda Workshop Manual GJ5G). The 8th VIN digit typically indicates engine displacement ('L' for 2.5L). Visually, the JJM has a compact inline-four layout with "SKYACTIV-G" branding on the plastic engine cover. Critical differentiation from the smaller Skyactiv-G 2.0L: The JJM has a larger displacement (2.5L vs 2.0L) and a different engine block casting. Service parts like manifolds and sensors are generally interchangeable within the Skyactiv-G family but verify part numbers against the EPC using the VIN.
The JJM's primary reliability consideration is intake valve carbon buildup, with elevated incidence in vehicles subjected to frequent short trips. Mazda internal data indicated a correlation between driving patterns and carbon accumulation, while UK DVSA records show no systemic mechanical failures for this engine. Adhering to the severe service maintenance schedule is critical for long-term smooth operation.
Analysis derived from Mazda technical bulletins (2015-2020) and UK DVSA failure statistics (2018-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MAZDA JJM.
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 MAZDA 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.
MAZDA 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 officialMAZDA 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.
