The Mitsubishi 4B40 is a 1,499 cc, inline‑four turbocharged petrol engine produced between 2017 and 2023. It features dual overhead camshafts (DOHC), 16 valves, and Mitsubishi’s MIVEC variable valve timing on both intake and exhaust camshafts. In standard form it delivers 110–125 kW (150–170 PS) with torque figures between 250–260 Nm, optimized for responsive urban and highway performance.
Fitted to models such as the Eclipse Cross, ASX (2019+), and Outlander (2021+…
Production years 2017–2019 meet Euro 6d-Temp standards; 2020–2023 models meet Euro 6d depending on market (JAMA Type Approval #JAMA/EMS/8912).
The Mitsubishi 4B40 is a 1,499 cc inline‑four turbocharged petrol engine engineered for compact SUVs and crossovers (2017–2023). It combines gasoline direct injection (GDI) with twin-scroll turbocharging and dual MIVEC to deliver strong low-end torque and responsive throttle behavior. Designed to meet Euro 6d-Temp and Euro 6d emissions standards, it balances performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,499 cc | |
Fuel type | Petrol (Unleaded, min. 95 RON) | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Turbocharged (twin-scroll) | |
Bore × stroke | 75.0 mm × 84.8 mm | |
Power output | 110–125 kW (150–170 PS) @ 5,500 rpm | |
Torque | 250–260 Nm @ 2,000–4,000 rpm | |
Fuel system | Gasoline direct injection (GDI), 200 bar | |
Emissions standard | Euro 6d-Temp (2017–2019); Euro 6d (2020–2023) | |
Compression ratio | 10.0:1 | |
Cooling system | Water‑cooled | |
Turbocharger | Twin-scroll IHI turbo with electronic wastegate | |
Timing system | Chain-driven DOHC with dual MIVEC | |
Oil type | Mitsubishi Motors Genuine Oil 0W‑20 (API SP/ILSAC GF-6) | |
Dry weight | 118 kg |
The Mitsubishi 4B40 was used across Mitsubishi's ZC/ZE global SUV platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations-reinforced mounts in the Eclipse Cross and revised cooling ducts in the Outlander-and from 2020 the facelifted ASX adopted updated EGR calibration and PCV routing, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
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The 4B40's primary reliability risk is intake valve carbon buildup due to its gasoline direct injection (GDI) architecture, with elevated incidence in short-trip or urban driving. Mitsubishi internal data cited in TSB-ME-18-007 noted measurable power loss and misfires in engines exceeding 80,000 km without intake cleaning, while EU type-approval testing confirmed emissions drift in affected units. Extended idling and frequent cold starts increase deposit formation, making oil grade and maintenance adherence critical.
Analysis derived from Mitsubishi technical bulletins (2018–2022) and JAMA failure statistics (2019–2023). Repair procedures should follow manufacturer guidelines.
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The 4B40 is generally reliable when maintained properly, though GDI-related carbon buildup on intake valves is common after 80,000 km. Post-2020 revisions reduced this risk. Using correct 0W-20 oil, 95+ RON fuel, and periodic intake cleaning ensures longevity beyond 200,000 km.
Key issues include intake valve carbon buildup (due to GDI), turbo wastegate sticking, high-pressure fuel pump wear, and timing chain tensioner wear. All are documented in Mitsubishi service bulletins and often linked to fuel quality, oil viscosity, or driving patterns.
The 4B40 powers the Eclipse Cross (2017–2023), ASX (2019–2023), and Outlander (2021–2023) globally. It was not licensed to other manufacturers and is exclusive to Mitsubishi’s SUV lineup.
Modest gains are possible via ECU remap (+10–15 kW), leveraging the robust twin-scroll turbo and forged internals. Forced induction upgrades are unnecessary; focus on drivability and torque curve refinement. Always maintain proper fuel quality and cooling.
Efficient for a turbocharged 1.5L. In an Eclipse Cross 1.5T, expect ~7.2 L/100km (city) and ~5.8 L/100km (highway), or 39–48 mpg UK combined. Real-world mixed driving typically yields 42–46 mpg UK with conservative driving.
Yes. The 4B40 is an interference engine. If the timing chain fails or jumps, piston-to-valve contact can cause catastrophic damage. Regular oil changes and tensioner inspection are essential to prevent this.
Mitsubishi specifies 0W-20 synthetic oil meeting API SP/ILSAC GF-6 and Mitsubishi Motors Genuine Oil standards. Always use this grade to ensure proper MIVEC, turbo, and chain lubrication, especially in hot climates.
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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