The Mitsubishi 4B12 is a 2,360 cc, inline‑four naturally aspirated petrol engine produced between 2007 and 2017. 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 delivered 125–128 kW (170–174 PS) and torque figures between 226–232 Nm, offering smooth mid‑range performance and refined cruising.
Fitted to models such as the Mitsubishi Lancer (including the Ral…
Production years 2007–2010 meet Euro 4 standards; 2011–2017 models meet Euro 5 depending on market (JAMA Type Approval #JAMA/EMS/4B12).
The Mitsubishi 4B12 is a 2,360 cc inline‑four naturally aspirated petrol engine engineered for compact and mid‑size SUVs and sedans (2007–2017). It combines DOHC with dual‑MIVEC variable valve timing to deliver smooth mid‑range torque and refined highway cruising. Designed to meet Euro 4 (early builds) and Euro 5 (later builds) standards, it balances performance with emissions compliance.
| 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 | 125–128 kW (170–174 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 (2011–2017) | |
Compression ratio | 10.5:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain‑driven DOHC | |
Oil type | API SN/ILSAC GF‑5, SAE 5W‑30 | |
Dry weight | 142 kg |
The Mitsubishi 4B12 was used across Mitsubishi's Global Compact and SUV platforms with transverse mounting. This engine received platform-specific adaptations—reinforced engine mounts in the Lancer Ralliart and revised oil pan baffling in the Outlander—and from 2011 the facelifted ASX adopted updated timing components, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
The 4B12's primary reliability risk is timing chain tensioner wear in early builds (2007–2010), with elevated incidence in high-mileage or extended-oil-interval use. Mitsubishi internal quality data from 2012 indicated up to 9% of pre-2011 engines exhibited audible chain rattle before 150,000 km, while EU type-approval testing confirmed revised tensioners reduced this to <2% in post-2011 units. Extended oil change intervals and low-viscosity oil accelerate tensioner degradation, making oil specification and interval adherence critical.
Analysis derived from Mitsubishi technical bulletins (2008–2015) and EU type-approval failure statistics (2010–2020). Repair procedures should follow manufacturer guidelines.
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The 4B12 is generally reliable if maintained properly, but early models (2007–2010) had timing chain tensioner wear issues. Post-2011 revisions resolved this with updated materials. Regular oil changes with correct 5W-30 oil and timely service greatly improve longevity and prevent common failures.
Key issues include timing chain tensioner wear (early builds), throttle body carbon buildup, valve cover gasket leaks, and exhaust manifold heat shield rattles. These are documented in Mitsubishi service bulletins SB‑08‑09‑012 and related TIS entries.
The 4B12 powered the Mitsubishi Lancer (2007–2017), Outlander (2007–2012), and select European ASX models (2010–2017). It was also used in platform-sharing Peugeot 4008 and Citroën C4 Aircross, though only in diesel variants; the petrol 4B12 remained exclusive to Mitsubishi.
Limited tuning potential due to naturally aspirated design. ECU remaps yield modest gains (+5–8 kW), but require careful calibration. Forced induction is not recommended without extensive internal modifications. Most owners prioritize smoothness and reliability over power.
Moderate for its size. In a Lancer 2.4 (2010), typical consumption is ~9.2 L/100km (city) and ~6.3 L/100km (highway), or about 34 mpg UK combined. Real-world mixed driving typically returns 28–36 mpg (UK) when maintained properly.
Yes. The 4B12 is an interference engine. If the timing chain fails or jumps, piston-to-valve contact can cause severe internal damage. However, the chain is designed for life-of-engine service if correct oil and intervals are maintained.
Mitsubishi specifies SAE 5W-30 oil meeting API SN/ILSAC GF-5 (or ACEA A5/B5). Always use a quality low-SAPS synthetic and change every 10,000 km or 12 months to protect the timing system and minimize oil consumption.
Comprehensive technical documentation and regulatory references
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MITSUBISHI Official Site
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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.
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