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+), the 4B40 was engineered to replace the naturally aspirated 4J1 series with enhanced low-end torque, improved fuel economy, and reduced CO₂ emissions. Emissions compliance was achieved through direct fuel injection (GDI), a close-coupled three-way catalytic converter, and cooled exhaust gas recirculation (EGR), enabling Euro 6d-Temp and later Euro 6d compliance depending on model year and market.
One documented concern is carbon buildup on intake valves due to the gasoline direct injection (GDI) system, which bypasses fuel detergent exposure on the back of valves. This issue, noted in Mitsubishi Service Bulletin TSB-ME-18-007, can lead to rough idle and reduced efficiency over time. From 2020 onward, Mitsubishi implemented revised EGR calibration and updated PCV routing to mitigate deposit formation.
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 twin-scroll turbo and dual MIVEC provide strong mid-range torque ideal for urban and highway overtaking but require strict adherence to 10,000 km oil change intervals to prevent sludge in the VVT system and turbo bearing wear. Mitsubishi-spec 0W-20 oil is critical due to its low viscosity aiding cold-start lubrication of the chain-driven DOHC system. Extended high-load operation in hot climates may accelerate oil degradation; owners in such regions should consider 7,500 km intervals. The GDI system lacks intake valve cleaning from fuel detergents, so periodic walnut blasting or intake cleaning is recommended after 80,000 km. Revised EGR maps from 2020 reduce carbon buildup per TSB-ME-18-007.
Oil Specs: Requires Mitsubishi Motors Genuine Oil 0W-20 meeting API SP/ILSAC GF-6 (Mitsubishi Service Bulletin TSB-LU-19-002).
Emissions: Euro 6d-Temp certification applies to 2017–2019 models only (JAMA Type Approval #JAMA/EMS/8912). Euro 6d compliance confirmed for 2020–2023 builds in EU markets.
Power Ratings: Measured under ISO 1585 standards. Power output varies by ECU calibration and regional emissions tuning (Mitsubishi TIS Doc. ME-4B40-04).
Mitsubishi Technical Information System (TIS): Docs ME-4B40-01, ME-4B40-02, ME-4B40-03, TSB-ME-18-007
JAMA Type Approval Database (JAMA/EMS/8912)
ISO 1585: Road vehicles — Engine test code — Net power
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.
Locate the engine code stamped on the front timing cover near the crankshaft pulley (Mitsubishi TIS ME-4B40-02). The 8th VIN digit indicates engine displacement ('4' for 1.5L 4B40). Early models (2017–2019) have silver valve covers with black intake manifolds; post-2020 units use all-black covers. Critical differentiation from 4J1: 4B40 is turbocharged with GDI and MIVEC on both cams; 4J1 is naturally aspirated and port-injected. Service parts for PCV and EGR differ pre/post 2020 per TSB-ME-18-007.
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.
Find answers to most commonly asked questions about MITSUBISHI 4B40.
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