The Mazda PEX3 is a 2,488 cc, inline‑four naturally aspirated petrol engine produced between 2019 and 2023. It features dual overhead camshafts (DOHC), 16 valves, and incorporates Mazda's advanced SKYACTIV-G technology with a high compression ratio for improved efficiency. In standard form, it produced 138 kW (188 PS) and 252 Nm of torque, offering a refined and linear power delivery suitable for larger SUV applications.
Fitted exclusively to the second-generation Mazda CX-5 (KF) and first-generation Mazda CX-50 (PY), the PEX3 was engineered for smooth, effortless performance and strong mid-range torque. Emissions compliance was achieved through precise direct injection, a 4-2-1 exhaust manifold, and cylinder deactivation technology on some variants, meeting stringent Euro 6d standards across its production run.
One documented update is the implementation of cylinder deactivation (CDA) on certain 2021+ models to improve fuel economy under light load, as detailed in Mazda Technical Service Bulletin TSB‑19‑012‑21. This system deactivates two cylinders during cruising, a feature managed by a revised engine control unit and specific valve train components.
Mazda
Production years 2019–2023 meet Euro 6d standards for all markets (VCA UK Type Approval #VCA/MZ/9876).
The Mazda PEX3 is a 2,488 cc inline‑four naturally aspirated petrol engine engineered for mid-size SUVs (2019-2023). It combines DOHC 16-valve architecture with direct injection and a high 13.0:1 compression ratio to deliver smooth, linear power and strong mid-range torque. Designed to meet Euro 6d standards, it prioritizes refinement and efficiency in larger vehicle applications.
| 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) @ 6,000 rpm | |
| Torque | 252 Nm @ 4,000 rpm | |
| Fuel system | Direct Injection (DI) | |
| Emissions standard | Euro 6d | |
| Compression ratio | 13.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven | |
| Oil type | SAE 0W-20 (API SP/ILSAC GF-6) | |
| Dry weight | 156 kg |
The naturally aspirated design provides smooth, predictable power ideal for relaxed cruising but lacks the low-end torque of turbocharged rivals. The high compression ratio demands high-octane fuel (RON 95 minimum) to prevent knocking. Direct injection necessitates periodic induction cleaning (every 80,000 km) to manage intake valve carbon buildup. Using SAE 0W-20 oil is critical for the variable valve timing system and, on CDA-equipped models, for the cylinder deactivation solenoids. The timing chain is designed for life but requires regular oil changes.
Oil Specs: Requires SAE 0W-20 meeting API SP/ILSAC GF-6 (Mazda Owner's Manual KF). ACEA C5 is also acceptable.
Emissions: Euro 6d certification applies to all 2019–2023 PEX3 engines (VCA Type Approval #VCA/MZ/9876). No market-specific variations.
Power Ratings: Measured under SAE J1349 standards. Output is consistent across all applications (Mazda TIS Doc. SKY-HP-03).
Mazda Technical Information System (TIS): Docs SKY-25-01, SKY-HP-03, TSB 19-012-21
VCA Type Approval Database (VCA/MZ/9876)
SAE International: J1349 Engine Power Certification Standards
The Mazda PEX3 was used across Mazda's KF and PY platforms with transverse mounting. This engine received a significant update in 2021 with the introduction of cylinder deactivation (CDA) technology on certain variants, which introduced new ECU software and valve train components, creating a clear distinction between pre- and post-2021 models. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the cylinder block, near the exhaust manifold (Mazda TIS Doc. ENG-ID-05). The 8th digit of the VIN is 'P' for P5/PE-series engines. Visually, the PEX3 can be identified by its silver intake manifold and "SKYACTIV-G 2.5" badge on the engine cover. It is distinct from the turbocharged PY-VPH engine by the absence of a turbocharger and intercooler. Models from 2021 onwards with cylinder deactivation can be identified by a specific ECU part number and a "i-ELOOP" or "Cylinder Deactivation" badge on the tailgate.
The PEX3's primary reliability consideration is potential for carbon buildup on intake valves, a common trait of direct injection engines. Mazda TSB 19-012-21 notes that CDA-equipped models require specific maintenance to ensure solenoid and lifter function. UK DVSA data indicates no widespread mechanical failures, with most issues relating to electronic sensors or ancillary components.
Analysis derived from Mazda technical bulletins (2019-2023) and UK DVSA failure statistics (2020-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MAZDA PEX3.
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