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Mitsubishi Pajero: 4M40 2.8L EGR System Carbon Clogging and Inlet Manifold Restriction

4M40 2.8L EGR System Carbon Clogging and Inlet Manifold Restriction is a very common engine fault on the Mitsubishi Pajero on the 1993–1999 cars, and we rate it major. Putting it right costs $400 to $1,800 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
4M40
Years
1993–1999
Fuel
diesel
System
Engine

This page covers the Mitsubishi Pajero as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Mitsubishi Pajero faults39 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Intake manifold or EGR valve yet. We would rather show none than show a picture of a different part.

What goes wrong

The 4M40 EGR (exhaust gas recirculation) system accumulates heavy carbon deposits in the EGR valve, connecting passages, and inlet manifold progressively over time. High-mileage examples can have the inlet manifold nearly completely blocked, severely restricting airflow and reducing power output. The EGR valve can stick open or closed. Many owners permanently block the EGR system as a long-term fix; a professional manifold clean or replacement is required to restore full performance.

What you would notice

  • Rough idle and engine surging
  • Black smoke on acceleration
  • Reduced power and noticeably worse fuel economy
  • Diesel smell from the intake area
  • Engine hesitation or stumble under load

How to check it

Where to look. EGR valve on exhaust manifold side of engine, inlet manifold on top of engine

Shine a torch into the inlet manifold to check for carbon lining or near-blockage. Check whether an aftermarket EGR block-off plate has already been fitted. If a workshop inspection is possible: Remove the EGR valve and inspect for carbon fouling — a heavily coked valve with restricted passages is a fail.

Parts involved: Intake manifold, EGR valve.

What it costs to put right

$400 to $1,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the EGR valve or inlet manifold been cleaned or replaced?”
  • “Has an EGR block plate been fitted to address carbon build-up?”
  • “When was the last full service including air filter replacement?”

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.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Mitsubishi Pajero buyer questions

Is 4m40 2.8l egr system carbon clogging and inlet manifold restriction serious on a Mitsubishi Pajero?

We rate it major and very common on the Mitsubishi Pajero. The 4M40 EGR (exhaust gas recirculation) system accumulates heavy carbon deposits in the EGR valve, connecting passages, and inlet manifold progressively over time. High-mileage examples can have the inlet manifold nearly completely blocked, severely restricting airflow and reducing power output. The EGR valve can stick open or closed. Many owners permanently block the EGR system as a long-term fix; a professional manifold clean or replacement is required to restore full performance.

How much does it cost to fix on a Mitsubishi Pajero?

$400 to $1,800 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 1993–1999 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?

Shine a torch into the inlet manifold to check for carbon lining or near-blockage. Check whether an aftermarket EGR block-off plate has already been fitted. If a workshop inspection is possible: Remove the EGR valve and inspect for carbon fouling — a heavily coked valve with restricted passages is a fail. Look here: EGR valve on exhaust manifold side of engine, inlet manifold on top of engine