Mitsubishi Pajero: Common-rail 4M41 injector failure and suction control valve surging (NS-NX)
Common-rail 4M41 injector failure and suction control valve surging (NS-NX) is a common engine fault on the Mitsubishi Pajero on the 2006–2021 cars, and we rate it major. Putting it right costs $400 to $4,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 39 documented faults on the Mitsubishi Pajero.
- Vehicle
- Mitsubishi Pajero
- Engine
- 4M41
- Years
- 2006–2021
- Fuel
- diesel
- System
- Engine
What you are looking at
Example of the part — not this vehicleA common-rail diesel injector. Contamination damages the nozzle at the tip.
What goes wrong
The common-rail 3.2 DiD in NS-NX Pajeros is durable but its Denso fuel system is intolerant of dirty fuel. Injectors wear from 150,000 km, causing knock, smoke and rough running, and a failing suction control valve on the high-pressure pump causes classic surging at cruise - a very common and frequently misdiagnosed fault. An SCV is a few hundred dollars; a set of injectors properly fitted with new seals is thousands. Diesel-spec fuel filters changed on time are the cheapest insurance.
What you would notice
- Surging or hunting at steady cruise speed
- Diesel knock and rough idle
- Hard starting, white smoke when cold
- Black smoke under load
How to check it
Where to look. Injectors under the top engine cover; suction control valve on the injection pump, left side of engine
On the test drive hold a steady 80-100 km/h and feel for rhythmic surging (SCV). Cold-start it yourself and watch for smoke. Ask for records of fuel filter changes and any injector work with a diesel specialist, including whether new injector seals and washers were fitted.
What it costs to put right
$400 to $4,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.
Ask the seller
- “Has the suction control valve ever been replaced?”
- “Any injector work done, and were genuine Denso parts used?”
- “How often were fuel filters changed?”
Now check the Mitsubishi Pajero you are actually looking at
Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.
Where this comes from
- Pajero 4WD Club of Victoria forum - 'Suction control valve' thread
- Whirlpool Forums AU - Suction control valve discussion (archive 2489715)
- TL Ranger Diesel - 4M41 injector issue quick diagnosis
Mitsubishi Pajero buyer questions
Is common-rail 4m41 injector failure and suction control valve surging (ns-nx) serious on a Mitsubishi Pajero?
We rate it major and common on the Mitsubishi Pajero. The common-rail 3.2 DiD in NS-NX Pajeros is durable but its Denso fuel system is intolerant of dirty fuel. Injectors wear from 150,000 km, causing knock, smoke and rough running, and a failing suction control valve on the high-pressure pump causes classic surging at cruise - a very common and frequently misdiagnosed fault. An SCV is a few hundred dollars; a set of injectors properly fitted with new seals is thousands. Diesel-spec fuel filters changed on time are the cheapest insurance.
How much does it cost to fix on a Mitsubishi Pajero?
$400 to $4,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.
Which Mitsubishi Pajero years are affected?
Our research records this fault on the 2006–2021 Mitsubishi Pajero. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.
How do I check for it before I buy?
On the test drive hold a steady 80-100 km/h and feel for rhythmic surging (SCV). Cold-start it yourself and watch for smoke. Ask for records of fuel filter changes and any injector work with a diesel specialist, including whether new injector seals and washers were fitted. Look here: Injectors under the top engine cover; suction control valve on the injection pump, left side of engine