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4N15

4N15 Engine

Last Updated:
Engine
2442 cm3
Aspiration
Turbocharger, Intercooler
Fuel
Diesel
Fuel injection system
Diesel Commonrail
Power
181 hp @ 3500 rpm
Torque
430 Nm @ 2500 rpm
Cylinders
4
Valves
16, 4 per cylinder
Cylinders position
Inline
Valvetrain
MIVEC
Oil capacity
6.7 l
Coolant
7.7 l
Systems
Particulate filter

# Vehicles powered by this engine

Engine 4N15 2.4 DI-D (181 HP): Real-world experience, issues, fuel consumption and used-buying tips

Key points in short (TL;DR)

  • All-aluminum block: The 4N15 engine is a huge step forward compared to its older predecessor (4D56) – it’s lighter, quieter and significantly more reliable.
  • Timing chain instead of belt: This engine uses a chain that has proven to be very durable, which lowers regular maintenance costs.
  • MIVEC technology: One of the rare diesel engines with variable valve timing, which gives it better throttle response at low revs.
  • Problems in city driving: Like any modern diesel, the DPF filter and EGR valve suffer from soot build-up if the vehicle is used exclusively for short urban trips.
  • Expensive dual-mass flywheel: Versions with a manual gearbox have a dual-mass flywheel whose replacement is very expensive (depends on the market).
  • Reliable automatic: Aisin automatic gearboxes paired with this engine are extremely robust, provided the oil is changed on time.
  • Excellent off-road: With 430 Nm of torque, the engine has no problem hauling heavy pickup and SUV bodies, even under full load or when towing a trailer.

Contents

Introduction: About the 4N15 engine

The 4N15 engine, commercially also known as the 2.4 MIVEC Clean Diesel, represents the pinnacle of Mitsubishi engineering when it comes to workhorses and off-road vehicles. It was primarily installed in heavy-duty models – Mitsubishi L200 (Triton), Pajero Sport and Montero Sport, as well as the Fiat Fullback, which is essentially a rebadged L200. Its main task was to replace the legendary but outdated 2.5-liter 4D56 engine. With a new aluminum block, common-rail injection and an advanced MIVEC system (a rarity for diesel engines), this powerplant offers smoother operation, lower weight and significantly better efficiency.

Technical specifications

Engine code 4N15
Engine displacement 2442 cc
Power output 133 kW (181 HP) at 3500 rpm
Torque 430 Nm at 2500 rpm
Injection type Common Rail Direct Injection
Camshaft drive Timing chain
Intake Turbocharger (VGT - Variable Geometry), Intercooler

Reliability and maintenance

One of the most common questions from owners concerns the timing system. To the delight of many, the 4N15 uses a timing chain instead of a belt. The chain has proven to be extremely robust and rarely causes headaches. There is no strictly defined interval for a “major service” in terms of chain replacement, but a visual inspection and listening to the tensioner is recommended after around 200,000 km. Still, a regular “major service” includes replacement of the auxiliary (serpentine) belt, tensioner, idler pulleys and water pump, which should be done every 100,000 to 120,000 km.

As for lubrication, this engine takes a fairly large amount of oil – about 8.4 liters. Only fully synthetic oil with a viscosity grade of 5W-30 or 0W-30 is recommended, meeting ACEA C2, C3 or C4 (Low SAPS) standards, which is crucial for preserving the DPF filter. Oil consumption is minimal; up to 0.5 liters between two 15,000 km service intervals is considered normal. If you notice that the engine consumes more, the problem usually lies in the turbo seals or, much more rarely, in worn piston rings due to severe overheating.

The injection system relies on Denso common-rail injectors. They have proven to be very reliable and, with quality Euro diesel fuel, can last between 200,000 and 250,000 km. Symptoms of worn injectors include rough idle, increased black smoke under hard acceleration, and more difficult cold starts.

Specific components and failures

When it comes to potential failures, the core engine itself is virtually bulletproof, but the peripheral components require attention. The engine is equipped with a single turbocharger with variable geometry (VGT). Turbo lifespan is directly linked to oil quality and driving style. If the driver switches off the engine immediately after hard driving under load (instead of letting it idle for a minute or two to cool the turbo), the turbo bearings will suffer damage. A stuck variable geometry mechanism due to soot build-up causes so-called “turbo lag” (sluggish throttle response) and can trigger “limp mode” (safety mode).

This powerplant has both an EGR valve and a DPF filter. Urban driving is their worst enemy. The EGR valve tends to clog with soot at around 80,000 to 100,000 km, which chokes the engine and causes jerking. Preventive cleaning of the intake manifold and EGR is recommended. On vehicles driven mostly in the city, the DPF filter often initiates regeneration; if this process is repeatedly interrupted by switching the engine off, excess fuel can end up in the oil sump and raise the oil level.

On newer versions (usually Euro 6 and facelift models after 2019), a AdBlue (SCR) system is also fitted. This system can cause issues with NOx sensors or the heater in the tank pump. Symptoms include an AdBlue warning light on the dashboard and a countdown of remaining kilometers until the engine can no longer be started. Replacing the module or pump is very expensive (depends on the market).

Fuel consumption and performance

Although the 4N15 is very efficient, it powers vehicles that often weigh over 2 tons and have aerodynamics similar to a brick. Real-world city fuel consumption ranges between 9.5 and 11 l/100 km. On open roads and highways, consumption can drop to a very decent 7 to 8 l/100 km.

The engine is definitely not sluggish. With 181 HP and a hefty 430 Nm available from just 2500 rpm, thanks to MIVEC technology the throttle response is surprisingly sharp for a pickup. There is more than enough power even when the bed is fully loaded or when towing a trailer. On the motorway, at 130 km/h, the engine runs smoothly and cruises at around 2100 to 2400 rpm (depending on whether the vehicle has a 5-speed, 6-speed or newer 8-speed automatic). Above that speed, fuel consumption rises sharply due to high aerodynamic drag.

Additional options and modifications

Off-road enthusiasts and those who tow heavy loads often ask about remapping. This engine has huge potential and a fairly large safety margin. A quality Stage 1 remap can safely raise power from 181 HP to around 210 to 220 HP, and torque from 430 Nm to around 500 Nm. It is important to note that if you have an automatic transmission, the tuning map must limit torque in the lower gears in order to protect the valve body and clutch packs inside the gearbox.

Gearbox and drivetrain

With the 4N15 you will most commonly find a 6-speed manual gearbox or automatic transmissions (the older 5-speed Aisin, or newer 6-speed and 8-speed automatics, depending on model and year).

If you are buying a version with a manual gearbox, keep in mind that this engine uses a dual-mass flywheel. Due to the high torque and heavy-duty work typical for pickup trucks, the clutch and flywheel are subjected to huge loads. When the flywheel starts to fail, you will feel strong vibrations when setting off, rattling at idle and thumps when switching the engine off. Replacing the clutch kit and dual-mass flywheel is very expensive (depends on the market).

On the other hand, Aisin automatic transmissions (traditional torque-converter automatics) are virtually indestructible, but only if properly maintained. The automatic transmission fluid must be changed every 60,000 to 80,000 km. If this is neglected, the valve body suffers damage from metal particles in the old oil, which leads to harsh shifts. The oil in the manual gearbox and transfer case (4x4 transfer box) should be replaced every 60,000 km.

Buying used and conclusion

When buying a used vehicle with the 4N15 engine, focus on a cold start. Ask the seller not to start the vehicle before you arrive. When starting, listen carefully for the first few seconds – metallic rattling indicates a stretched chain or a weak hydraulic tensioner. After that, under full throttle while driving, check the rear-view mirror; black smoke points to injector issues or a clogged intake/EGR, while bluish smoke suggests oil consumption through the turbo.

Be sure to check the operation of Mitsubishi’s fantastic Super Select 4WD system (if the vehicle is equipped with it). Switching between rear-wheel drive, four-wheel drive and low range should be smooth, without loud metallic bangs or warning lights staying on in the instrument cluster.

Who is it for? The 4N15 engine in the L200, Pajero Sport and Fiat Fullback is a fantastic workhorse. It is intended for people who need raw power for off-road driving, towing and harsh conditions, and who are not willing to compromise on modern comfort and reliability. If you only need a vehicle to “pose” around town and go to cafés, the DPF and EGR will quickly get back at you. However, if you use it for what it was designed for, with regular maintenance and quality oil, this is one of the most reliable Japanese diesels in its class.

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