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Mitsubishi 4N15 engine: known problems
Used in 2 guides · 2442cc diesel · 9 known problems
Displacement
2442cc
Layout
I4 turbo
Fuel
diesel
Timing
Chain-driven (no belt). Valve clearance check every 60,000km
Known problems9
Everything our guides list for the variants with this engine: the engine itself plus the gearbox and ancillaries it's paired with. Each shows which cars it's listed for.
High
Cracked cylinder head / head gasket
Not common but documented - cracked heads or blown head gaskets, with one theory being mechanics over-torquing injector hardware or forcing stuck injectors, plus heat stress on hard-worked engines.
Fix: Use a diesel specialist for injector work; investigate any coolant loss, overheating or white smoke immediately. Head repair/replacement if cracked.
Listed for: Mitsubishi Pajero Sport QE / QF
Medium
Split / blown intercooler hose
The factory intercooler pipe/hose is the single most common fault on the QE - it splits or pops off, triggering limp mode, loss of boost and a sudden drop in power.
Fix: Replace with an upgraded aftermarket silicone intercooler hose; cheap insurance and a popular preventive fix.
Listed for: Mitsubishi Pajero Sport QE / QF
Medium
DPF clogging / EGR soot (short-trip use)
Stop-start, low-speed city driving prevents the DPF from regenerating, leading to clogging, repeated regen warnings, limp mode and EGR/intake soot. Faulty DPF temperature sensors have also been reported.
Fix: Drive at highway speed ~20+ minutes at least monthly to complete regen; forced regen, DPF/EGR clean or sensor replacement if clogged. Not the right vehicle for city-only short trips.
Listed for: Mitsubishi Pajero Sport QE / QF
Medium
Valve clearances tightening (60,000km check)
The 4N15's valve clearances tend to tighten over time and must be checked/adjusted every 60,000km; skipping this risks burnt valves and major engine damage down the track.
Fix: Have the 60,000km valve clearance inspection done on schedule by a Mitsubishi-savvy mechanic; confirm it in the service history before buying.
Listed for: Mitsubishi Pajero Sport QE / QF
Medium
DPF / EGR issues on short-trip use
Like the QE, the QF's DPF needs regular highway running to regenerate. City-only short trips cause clogging, regen warnings and limp mode; EGR and intake soot can build up.
Fix: Regular sustained highway driving for regen; DPF/EGR service or sensor replacement if clogged.
Listed for: Mitsubishi Pajero Sport QE / QF
Medium
Valve clearance tightening (60,000km)
The 4N15 still requires a valve clearance check/adjustment every 60,000km to avoid tight valves and long-term damage.
Fix: Keep the 60,000km valve clearance service up to date; verify in the records pre-purchase.
Listed for: Mitsubishi Pajero Sport QE / QF
Medium
DPF regen failure (MR models)
Post-2018 MR models driven primarily on short urban trips frequently fail to complete passive DPF regen cycles. Result: soot loading, warning lights, engine limp mode.
Fix: Forced manual regen via diagnostic tool, off-car chemical clean, or full DPF replacement if internally melted. Long highway runs help on a healthy DPF.
Listed for: Mitsubishi Triton MQ / MR
Medium
Intake manifold carbon fouling
Oil mist from crankcase ventilation combines with hot EGR gases to build carbon inside the intake manifold, restricting airflow.
Fix: Intake manifold off, manual clean or ultrasonic media blast.
Listed for: Mitsubishi Triton MQ / MR
Low
Intercooler hose splitting
Factory rubber intercooler hoses soften and split under boost. Symptoms: sudden boost leak, black smoke, power loss.
Fix: Replace with heavy-duty silicone aftermarket hoses.
Listed for: Mitsubishi Triton MQ / MR
Cars with the 4N152
From the FlamingCars guides for these cars. Specs are shown only where the guides agree and the value is verified.