The Mazda CAY1 is a 2,488 cc, inline‑four naturally aspirated petrol engine introduced in 2019 for the CX — 5 and Mazda6. It features a dual overhead camshaft (DOHC) design with 16 valves and Mazda's Skyactiv — G technology, prioritizing high compression and thermal efficiency. Output is rated at 140 kW (190 PS) with 252 Nm of torque, delivered with a linear, responsive character ideal for highway cruising and daily commuting.
Fitted to the CX — 5 (KF) and Mazda6 (GJ) facelift…
Mazda
Production years 2019–Present meet Euro 6d-TEMP and Euro 6d standards depending on model year and market .
The Mazda CAY1 is a 2,488 cc inline‑four naturally aspirated petrol engine engineered for mid-size SUVs and sedans (2019-Present). It combines Skyactiv-G technology with direct injection and a high 13:1 compression ratio to deliver smooth, linear power and class-leading fuel efficiency. Designed to meet stringent Euro 6d emissions standards, it offers a refined and responsive driving experience.
| 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 | 140 kW (190 PS) | |
Torque | 252 Nm @ 4,000 rpm | |
Fuel system | Direct Injection (Skyactiv-G) | |
Emissions standard | Euro 6d-TEMP / Euro 6d | |
Compression ratio | 13.0:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain-driven | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | Not publicly specified |
The Mazda CAY1 was introduced for Mazda's KF and GJ facelift platforms with transverse mounting. This engine replaced the earlier 2.5L Skyactiv-G unit, featuring updated internals and emissions systems. All adaptations are documented in OEM technical bulletins.
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The CAY1 is generally robust, with its primary documented concern being the high-pressure fuel pump in early units. While designed for longevity, proactive maintenance like intake valve cleaning is recommended. OEM service schedules are critical, as neglect can lead to reduced performance and efficiency.
Analysis derived from Mazda technical bulletins (2019-Present) and workshop manuals. 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
Yes, the CAY1 is considered a very reliable engine. Its primary known issue, the early HPFP noise, is addressed by a service bulletin. With regular oil changes using the correct 0W-20 specification and periodic intake valve cleaning, these engines are expected to provide trouble-free service for well over 200,000 km.
The most documented issues are the noisy high-pressure fuel pump in early production units (fixed by TSB), gradual intake valve carbon buildup requiring cleaning, minor oil consumption inherent to its high-compression design, and occasional VVT actuator rattle on cold starts. All are manageable with proper maintenance.
The CAY1 engine is used in the facelifted Mazda CX-5 (KF series) from 2019 to present and the facelifted Mazda6 (GJ series) from 2019 until its discontinuation in 2023. It is the standard 2.5L naturally aspirated petrol engine for these models in most global markets.
While not as common as tuning the turbocharged variant, the CAY1 can see modest gains. A performance ECU remap can yield around 10-15 additional horsepower by optimizing ignition and fuel maps. More significant power increases require forced induction, which is a complex and costly modification.
It offers excellent fuel economy for its size. In a typical CX-5 AWD, expect combined fuel consumption of around 7.5-8.5 L/100km (33-38 mpg UK). Front-wheel-drive models and highway driving can see figures as low as 6.5 L/100km (43 mpg UK), making it very efficient for a 2.5L engine.
Yes, the CAY1 is an interference engine. This means if the timing chain were to fail or jump timing, the pistons could collide with the open valves, causing severe internal engine damage. Fortunately, the timing chain is designed to last the engine's lifetime with proper oil maintenance.
Mazda mandates the use of SAE 0W-20 engine oil meeting the latest API SP (or ILSAC GF-6A) specification. This low-viscosity oil is critical for the Skyactiv-G engine's efficiency, performance, and longevity. Using a thicker oil can reduce fuel economy and potentially cause damage.
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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