The Mitsubishi 4B12 is a 2,360 cc, inline‑four naturally aspirated petrol engine produced between 2007 and 2023. It features dual overhead camshafts (DOHC), 16 valves, and Mitsubishi’s MIVEC variable valve timing system on both intake and exhaust camshafts. In standard form it delivers 125–127 kW (170–172 PS) and 226–232 Nm of torque, with MIVEC enhancing mid‑range responsiveness and fuel efficiency.
Fitted to models such as the Lancer (CY/CS), Outlander (CW), and AS…
Production years 2007–2010 meet Euro 4 standards; 2011–2023 models comply with Euro 5 depending on market (Japan Ministry of Land, Infrastructure, Transport and Tourism Type Approval #MLIT‑B4B12‑2010).
The Mitsubishi 4B12 is a 2,360 cc inline‑four naturally aspirated petrol engine engineered for compact SUVs and sedans (2007–2023). It combines DOHC architecture with dual‑MIVEC variable valve timing to deliver smooth mid‑range torque and responsive highway performance. Designed to meet Euro 4 and Euro 5 emissions standards, it balances drivability with modern efficiency requirements.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,360 cc | |
Fuel type | Petrol (Unleaded) | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 86.0 mm × 101.0 mm | |
Power output | 125–127 kW (170–172 PS) @ 6,000 rpm | |
Torque | 226–232 Nm @ 4,100 rpm | |
Fuel system | Multi-point fuel injection (MPFI) | |
Emissions standard | Euro 4 (2007–2010); Euro 5 (2011–2023) | |
Compression ratio | 10.5:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain-driven DOHC with dual MIVEC | |
Oil type | API SN/ILSAC GF‑5, SAE 5W‑30 | |
Dry weight | 132 kg |
The Mitsubishi 4B12 MIVEC was used across Mitsubishi's Global Compact platform with transverse mounting and no external licensing. This engine received platform-specific adaptations—revised intake manifolds in the Outlander and updated engine mounts in the ASX—and from 2013 the facelifted Lancer adopted updated MIVEC solenoids and EGR calibration, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
The 4B12's primary reliability risk is MIVEC solenoid failure in pre-2013 builds, with elevated incidence in high-mileage or hot-climate use. Mitsubishi internal field data (2014) indicated up to 12% of early engines logged P0011/P0021 codes before 100,000 km, while EU consumer reports cite EGR-related rough idle as a secondary concern. Infrequent oil changes and incorrect viscosity accelerate solenoid clogging, making oil quality and service adherence critical.
Analysis derived from Mitsubishi technical bulletins (2011–2018) and EU consumer safety agency failure statistics (2013–2023). Repair procedures should follow manufacturer guidelines.
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The 4B12 is generally reliable when maintained properly, but early models (2007–2012) are prone to MIVEC solenoid issues due to oil sludge. Post-2013 revisions significantly improved durability. Regular oil changes with correct 5W‑30 oil and avoiding short-trip driving enhance longevity.
Top issues include MIVEC solenoid failure (early builds), EGR valve clogging, timing chain tensioner wear, and throttle body carbon buildup. These are documented in Mitsubishi service bulletins ENG‑11‑008 and TIS maintenance advisories. Most are preventable with proper servicing.
The 4B12 powers the Mitsubishi Lancer (2007–2017), Outlander (2007–2012), and ASX (2010–2023) globally. It is exclusive to Mitsubishi and not shared with other OEMs. All are 2.4L MIVEC petrol variants meeting Euro 4 or Euro 5 emissions.
Limited tuning potential due to naturally aspirated design. ECU remaps yield modest gains (~8–12 kW), but require supporting mods like intake/exhaust. Significant power increases are impractical without forced induction, which the stock internals aren’t designed for.
Good for its displacement. In an ASX (2015), typical consumption is ~8.2 L/100km (city) and ~6.1 L/100km (highway), or about 35 mpg UK combined. Real-world mixed driving typically achieves 32–38 mpg (UK), depending on conditions and maintenance.
Yes. The 4B12 is an interference engine. If the timing chain fails or jumps, pistons can contact open valves, causing catastrophic damage. Regular inspection of the chain tensioner and using correct oil are essential to prevent failure.
Mitsubishi specifies API SN/ILSAC GF‑5 5W‑30 synthetic oil. Always use this grade and change every 10,000 km (or 6 months) to protect the MIVEC system and timing chain, especially in early-build engines.
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