Common faults below

Mitsubishi Engine Carbon Cleaning

What we see most on Mitsubishi engines, what causes it, and which clean fixes it. Every job starts with a scan and a quote at our Kings Park workshop.

Mitsubishi engine carbon cleaning at Expert Carbon Cleaning, Kings Park Sydney
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Which Mitsubishi do you have?

Most of the Mitsubishis we see are Tritons and Pajero Sports with the 2.4-litre 4N15 diesel, and nearly all of them arrive with a version of the same problem.

It starts at the injectors. A tip that no longer sprays cleanly makes more soot, the soot loads the particulate filter, the filter tries to regenerate more often, and every regeneration that gets cut short washes diesel past the piston rings into the sump. That is why so many owners find the oil level going up. It is one fault with three faces, and treating any one of them alone does not hold.

If you have an Outlander PHEV, none of that applies. The petrol engine there works more like a generator than a drivetrain, and it has its own kind of build-up.

And if you have a petrol ASX, Eclipse Cross or Outlander, the issue is intake-side carbon, not the exhaust.

We scan the vehicle first and tell you the cost before we start.

Common Mitsubishi carbon problems

What we see

If you drive a petrol Mitsubishi

Petrol

Intake Valve Carbon on the Petrol Models

  • The direct-injection petrol engines spray fuel into the cylinder, so nothing washes the back of the intake valves.
  • Oil vapour from the breather settles on the hot valve and bakes into a crust.
  • Short city trips build it up faster than highway kilometres.
  • Lumpy idle, worst from cold.
  • Hesitation off the line and softer throttle response.
  • Misfire codes (P0300–P0304) with the ignition side checking out fine.
  • Walnut blasting once the deposits have hardened — the intake comes off and each port is cleaned mechanically.
  • A hydrogen carbon clean will keep on top of it if you start before the crust forms.

Fixed by

Walnut Blasting

Quoted after the free scan

See the service →

If you drive a diesel Mitsubishi

Diesel

Oil Level Rising on the 2.4 Diesel

  • During a regeneration the engine injects extra diesel late in the cycle to heat the exhaust. If the run is cut short, some of that fuel washes past the rings into the sump.
  • On the 4N15 the usual reason regenerations keep failing is the injectors — a tip that sprays poorly makes more soot and starts the whole cycle again.
  • Diluted oil is thinner than the engine needs, so it protects the turbo and bearings less well the longer it goes on.
  • Oil above the full mark when you have added none.
  • A diesel smell on the dipstick.
  • Service warnings arriving sooner than they should.
  • Rattly idle and smoke on start-up.
  • This is a fuel-side fault, not an oil fault — topping up or changing the oil treats the symptom.
  • We clean the whole fuel system on the vehicle so the injectors deliver properly and regenerations can finish.
  • If your oil is diluted, do not put off the oil change. Thin oil is what turns this from an annoyance into an expensive repair.

Fixed by

Diesel Injector Cleaning

Quoted after the free scan

See the service →
Diesel

Particulate Filter Blockage on the Triton and Pajero Sport

  • A regeneration needs a sustained uninterrupted run. School runs, site work and short trips never provide one.
  • Poor injector spray loads the filter faster than normal driving would, so the vehicle attempts regenerations more and more often.
  • Each abandoned attempt leaves the filter fuller than before.
  • DPF light, then reduced power and limp mode.
  • The gaps between warnings getting shorter.
  • Fuel consumption up and a hot smell after parking.
  • Codes in the P2002 and P2452–P2463 range.
  • Where we can, we clean the filter on the vehicle — nothing removed, cut open or replaced. If it has to come off, it gets a three-stage clean and new gaskets, quoted first.
  • We treat the fuel side in the same visit, because on a 4N15 the filter is usually the symptom rather than the fault.
  • Nothing is deleted. A vehicle without its emissions equipment is not roadworthy in New South Wales.

Fixed by

DPF Cleaning

From $715

See the service →
Diesel

EGR and Intake Manifold Coking

  • The EGR valve routes sooty exhaust gas back into the intake, where it meets oil mist from the breather.
  • The two combine into a thick, greasy deposit that narrows the runners.
  • Towing and low-speed four-wheel driving make it worse, because the deposit never burns off.
  • Poor throttle response, worst from low revs and under load.
  • Black smoke on acceleration.
  • Rough idle with EGR flow codes (P0401, P0402, P0403).
  • We clean the EGR circuit and the intake manifold so the airway is clear again.
  • On a Triton this is often what has been quietly limiting a ute everyone assumed was just tired.

Fixed by

EGR & Intake Manifold Cleaning

Quoted after the free scan

See the service →

If you drive a hybrid Mitsubishi

Hybrid

The Outlander PHEV Engine

  • In the Outlander PHEV the petrol engine spends much of its life charging the battery rather than driving the wheels, often at steady light load.
  • On short trips it may not start at all, and when it does it rarely gets properly hot.
  • Deposits build up at kilometre readings that look far too low to explain them.
  • Roughness when the engine cuts in.
  • The engine sounding busier or coarser than you remember.
  • A petrol smell at idle on a car that has done very little driving.
  • A hydrogen carbon clean suits this — nothing comes apart, and it works on soft carbon before it hardens.
  • On a PHEV this is prevention. The engine is not worn out, it is just never asked to clean itself.

Fixed by

Hydrogen Carbon Clean

$275

See the service →

Applies to any Mitsubishi

Any Mitsubishi

Short Trips, Towing and Stop-Start

  • A Mitsubishi doing school runs during the week and towing at the weekend gets the worst of both worlds — long periods too cool to stay clean, then heavy load on a dirty engine.
  • The intake, the filter and the fuel side get dirty together.
  • Fixing one and leaving the others just moves the problem along.
  • The same code returning after being cleared.
  • A vehicle that feels flat towing when it never used to.
  • Several unrelated-looking faults over a short period.
  • A full engine carbon clean treats the intake and exhaust sides together, which is the right scope when the whole engine is dirty rather than one part.
  • We scan first, tell you what we have found, and give you the cost before anything starts.

Fixed by

Full Engine Carbon Clean

From $715

See the service →

Watch us clean a Mitsubishi

Real jobs from our Kings Park workshop — the same work we would do on yours.

Keeping your Mitsubishi clean

Prevention

To keep a Triton or Pajero Sport with the 2.4-litre 4N15 diesel clean, start at the injectors. A tip that no longer sprays cleanly makes more soot, and the soot loads the particulate filter. A regular look at the oil level catches it early, and a hydrogen carbon clean is the maintenance step before carbon hardens. On the petrol ASX, Eclipse Cross and Outlander, the carbon builds on the intake valves instead.

If the oil level is climbing or the DPF light keeps coming back, book a time at our Kings Park workshop. We scan it free first, tell you what it needs, and quote before any work starts. On a 4N15 the fix is often a fuel system clean, with the filter treated in the same visit.

Just had a chemical clean done on my Mitsubishi challenger 2012 at 150,000ks. over half a cup of gunk was removed, i took it for a longer drive on the way home and the difference is noticeable especially when pulling up hills, Customer service was amazing and Nas was great at explaining everything so i knew what my options were before making them, totally recommend 10/10!

Ky Fisher (kyborgFTW), 2012 Mitsubishi Challenger · Google review

I have an 11 year old Mitsubishi Pajero with nearly 300k on the speedo. The engine management indicator came on and the car required some serious servicing. Naz analysed the issues, carried out the work required very professionally and at a very reasonable cost. I would have NO hesitation in recommending Naz and his team to be honest and professional. Thankyou Naz, the car runs as if it was brand new.

Steve Young, Mitsubishi Pajero · Google review

Before any engine work on your Mitsubishi, search your VIN on the government vehicle recalls site. Recall repairs are free, so check there first.

  • Check the dipstick regularly. Oil above the full mark when you have added none, or a diesel smell on the dipstick, usually means fuel is getting into the sump because the filter’s self-cleans are not finishing.
  • Change diluted oil straight away. Thin oil protects the turbo and bearings less, and that is what turns a clean into an expensive repair. It buys time; the fix is on the fuel side.
  • Give it a long run. School runs, site work and short trips never let the particulate filter finish its self-clean. Nas’s rule of thumb, a steady run of about half an hour every week, or an hour every fortnight, gives it the chance.
  • Fix the injectors, not just the filter. On the 4N15 a poor injector spray is usually why the filter keeps loading, so cleaning the filter on its own does not hold.

Book your Mitsubishi in

Get a free quote

Tell us the model, the kilometres and what it is doing. We will scan it and tell you which clean it needs, and what it costs, before any work starts.

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Tell Nas about your car

What are you driving, and what is it doing? Nas will call you back to talk it through — we scan the car at the workshop first, and nothing starts without your OK.

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