Mitsubishi Pajero Sport: common faults & what to check

Can't confirm for this car

The 2.4 4N15 in the current Pajero Sport (shared with Triton MQ/MR) has documented cases of the cylinder head cracking around the injector bores - the walls are thin, and carbon-stuck injectors that are forced out during the scheduled valve-clearance services (which require injector removal roughly every 40,000 km) can crack the head or leave injectors seating badly. Poor seating lets combustion gas blow past (chuffing noise, carbon 'chimneying' around the injector), and a cracked head means head replacement. Choose a vehicle whose injector work was done by people who knew this engine.

Example of the part — not this vehicle

Where to look: Cylinder head, injector bores under the top engine cover

Parts involved: Cylinder head, Fuel injector.

Can't confirm for this car

The 4D56 runs a second, inner toothed belt for the balance shafts, sitting behind the main timing belt. It is a consumable that has to be replaced at the same time as the timing belt, and it is routinely left in place to save an hour of labour. When it lets go it does not just stop the balance shafts: the shredded belt can wrap itself around the crankshaft pulley and jump or destroy the timing belt right next to it. The 4D56 is an interference engine, so a timing belt that jumps teeth or breaks lets the pistons hit the valves, and what should have been a belt service becomes a cylinder head rebuild. The two usual triggers are oil from a weeping front crankshaft seal soaking the belts, and incorrect tension at the last belt change - both Gates and Dayco publish Australian technical bulletins on getting the 4D56 procedure exactly right for precisely this reason.

Where to look: Behind the plastic timing cover at the front of the engine on the passenger side of the engine bay - the balance shaft belt is the inner belt, tucked behind the main timing belt. What you can actually see is the paperwork and any oil around the crankshaft pulley.

Parts involved: Timing belt.

Can't confirm for this car

A batch of 2011 to 2012 PB Challenger and Triton 4WDs had front propeller shafts made before 25 November 2011 with poor welds. If the weld fails the front shaft can break, damage the fuel pipe and cause a fuel leak and fire risk, and acceleration or braking can be affected. The Australian recall (PRA 2013/13844) covered 584 vehicles across both models and the fix is free at a Mitsubishi dealer.

Where to look: Under the car, front propeller shaft between the transfer case and the front differential, near the fuel pipe

Can't confirm for this car

The 4D56 common-rail diesel uses a Denso fuel system, and the suction control valve is the small electric valve on the inlet side of the high-pressure pump that meters how much fuel gets pressurised. It is a genuine wear item on this engine. As it goes off, rail pressure becomes unstable and the car starts to hunt at idle, surge under light throttle, and crank for a long time before firing — usually worse when the engine is already hot, which is the opposite of what most people expect. The fault code is P0089. The valve itself is not expensive, but the same symptoms can also mean tired injectors, which is a much bigger bill, so it is worth knowing which one you are looking at before you agree a price.

Where to look: Suction control valve on the side of the high-pressure fuel pump, at the belt end of the engine

Parts involved: Fuel rail, Fuel injector.

Can't confirm for this car

Some QE Pajero Sport owners report the 8-speed automatic shuddering or 'missing' at highway speeds in 6th, 7th and 8th gears - typically at light throttle around 90-110 km/h - with the symptom disappearing when 5th is manually selected. Causes reported range from torque converter lock-up shudder to software calibration, and Mitsubishi dealers have addressed cases with fluid changes and TCU updates. It is not universal, but it is exactly the kind of fault a short suburban test drive will never reveal, so get the vehicle to open-road speed before buying.

Where to look: Automatic transmission and torque converter, under the centre of the vehicle

Parts involved: Torque converter.

Can't confirm for this car

Like most common-rail diesels of its era, the Challenger's 4D56 recirculates sooty exhaust through the EGR valve, and combined with crankcase oil vapour it forms thick carbon sludge in the inlet manifold. The result is sluggish performance, higher fuel use, rough idle and eventually a sticking EGR valve triggering limp mode. A walnut-blast or manual inlet clean plus an EGR service restores it, and it will recur on a truck that only does short urban trips.

Where to look: EGR valve and inlet manifold on top/side of the engine

Parts involved: Intake manifold, EGR valve.

Can't confirm for this car

In November 2013 Mitsubishi recalled 20,405 Australian vehicles - 17,540 Tritons and 2,865 Challengers - from the 2011 and 2012 model years built before 11 May 2012. The front suspension lower control arms had been improperly welded, and the recall notice warned that the weld could fail, at which point the vehicle would become unstable and pull sharply to one side of the road. The Challenger campaign is PRA 2013/13840. The repair is free at a Mitsubishi dealer, but a vehicle this old has usually changed hands several times and a good number were never presented, so on a 2011 or 2012 Challenger this has to be confirmed against the VIN rather than assumed. It costs nothing to check and it is the single highest-value phone call you can make about this car.

Where to look: The front suspension lower control arms - the large A-shaped arms running from the chassis out to the bottom of each front wheel hub, behind and below the front bumper on each side.

Can't confirm for this car

2016 model year QE Pajero Sports were recalled (PRA 2016/15767) because the tailgate gas spring end caps did not have enough anti-corrosion coating. They can rust and break, and the tailgate can drop suddenly on someone. It applies to all engines. The fix was new gas springs at a Mitsubishi dealer.

Where to look: Tailgate gas struts

Parts involved: Body corrosion.

Can't confirm for this car

The Challenger shares Mitsubishi's rear axle design where side-shafts can move slightly outwards on their circlips and let diff oil escape past the seals, spraying the underside. Run dry, the diff howls and eventually fails. Rear diff whine rising with road speed on a Challenger should be treated as bearing or oil-starvation damage, not 'character'. Fixed early it is a seals-and-circlips job; left late it is a diff rebuild or second-hand diff swap.

Where to look: Rear differential and axle shaft flanges

Parts involved: Differential.