Common faults below

GWM Engine Carbon Cleaning

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

Free scanbefore any work
Kings ParkSydney workshop
20+ yrsMTA certified
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Which GWM do you have?

GWM is the newest brand on this page, and that is exactly why we see so many of them. Most GWMs in Sydney are only a few years old, and owners are surprised to be dealing with a blocked particulate filter on a vehicle that still feels new.

If you have a Cannon diesel, it is a 2.0-litre turbo diesel on the entry models and a 2.4 on the bigger ones. These are the ones we see most, and almost always for the same reason — a filter that has never had the chance to clean itself.

If you have a Haval H6, Jolion or Tank 300 petrol, it is a turbocharged direct-injection engine, and the problem is at the intake valves instead.

And if you have one of the hybrids — H6 Hybrid, Jolion Hybrid, Cannon Alpha or Tank 300 — the petrol engine spends much of its life at light load or switched off, which builds deposits in its own way.

We scan first and tell you what it will cost before we start.

Common GWM carbon problems

What we see

If you drive a petrol GWM

Petrol

Intake Valve Carbon on the Turbo Petrol

The turbocharged petrol engines in the H6, Jolion and Tank 300 inject fuel straight into the cylinder, so nothing washes the back of the intake valves.
Oil vapour from the breather bakes onto the hot valve and hardens into a crust.
City driving builds it up faster than highway kilometres.

Lumpy idle, worst when cold.
Hesitation off the line and softer throttle.
Misfire codes (P0300–P0304) with no ignition fault found.

Walnut blasting once the deposits have hardened — the intake comes off and each port is cleaned mechanically.
A hydrogen carbon clean will stay 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 GWM

Diesel

Blocked Particulate Filter on the Cannon Diesel

A regeneration needs a sustained run to burn soot out of the filter. A ute doing suburban trips and site work never gets one.
Once the filter is loaded, the ute protects itself by cutting power (limp mode). Owners report the DPF light coming back sooner each time, with a clear loss of power.
Each abandoned regeneration leaves the filter fuller than it started, so the gaps between warnings get shorter.

DPF light, then a clear loss of power.
The light coming back within days of a dealer clearing it.
Fuel consumption climbing, 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 is removed, cut open or replaced. If it has to come off, it gets a three-stage clean and new gaskets, quoted first.
GWM doesn’t publish a set interval for DPF burns. The Cannon burns its filter when enough soot builds up, so short, stop-start trips mean more burns and more interrupted ones. The 2.0 Cannon has a DPF button that runs the same parked burn we start with a scan tool. It helps when soot is the only problem. If the light keeps coming back, something is still feeding the filter, and that’s what our free scan finds.
We look at why it blocked. Cleaning a filter on a ute that still cannot finish a regeneration only buys you a few months.
Nothing is deleted or switched off. A ute 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 feeds sooty exhaust gas back into the intake, where it meets oil mist from the breather.
The two form a thick, greasy deposit that narrows the intake runners.
Towing and low-speed work make it worse, because the deposit never gets hot enough to burn away.

Flat throttle response, worst from low revs and when loaded.
Black smoke under acceleration.
Rough idle with EGR flow codes (P0401, P0402, P0403).

We clean the EGR circuit and intake manifold so the airway is clear again.
On a Cannon this is often what has been quietly strangling a ute everyone assumed was just underpowered.

Fixed by

EGR & Intake Manifold Cleaning

Quoted after the free scan

See the service →

Diesel

Injector Fouling and Hard Starting

Deposits on the injector tips spoil the spray pattern, so diesel arrives as droplets rather than a fine mist.
Incomplete combustion makes more soot, which loads the filter faster — the two problems feed each other.
Fuel quality and long periods parked both make it worse.

Hard starting, especially on a cold morning.
Rattly or uneven idle.
Smoke on start-up and worse economy.
Fuel rail pressure codes (P0087, P0088, P008A).

We clean the whole fuel system on the vehicle with the engine running — injectors, pump and rail — with nothing removed or sent away.
Separate from carbon: some 2023 Cannons were recalled (REC-006123) because the diesel fuel filter’s sealing ring can leak fuel. If yours is one, have the free repair done at a GWM dealer first. You can check your VIN on the government vehicle recalls site.

Fixed by

Diesel Injector Cleaning

Quoted after the free scan

See the service →

If you drive a hybrid GWM

Hybrid

Hybrids That Rarely Run the Engine Hard

In the H6 and Jolion hybrids, the Cannon Alpha and the Tank 300, the petrol engine starts and stops constantly and often runs at light load.
An engine that seldom reaches full working temperature builds soft carbon faster, even while using less fuel.
Because the car feels effortless, there is nothing to tell you it is happening.

Roughness as the engine cuts in and out.
The petrol engine sounding busier than the speed suggests.
Deposits at kilometre readings that look far too low.

A hydrogen carbon clean suits this well — nothing is dismantled, and it deals with soft carbon before it sets.
On a hybrid this is prevention, and it is much cheaper than the alternative later.

Fixed by

Hydrogen Carbon Clean

$275

See the service →

Applies to any GWM

Any GWM

A Nearly New Vehicle That Already Feels Tired

GWMs are young cars, so owners rarely suspect carbon — the assumption is that something is broken.
In practice the intake, the filter and the fuel side all get dirty together on a vehicle used for short trips.
Fixing one and leaving the others just moves the problem along.

The same code returning after being cleared.
Several unrelated-looking faults over a short period.
A vehicle that has been to more than one workshop with nothing sticking.

A full engine carbon clean covers both sides in one visit — the sensible scope on a vehicle too young to have a worn-out part but dirty enough to feel like it does.
You get the scan result and the price before we pick up a tool.

Fixed by

Full Engine Carbon Clean

From $715

See the service →

Keeping your GWM clean

Prevention

To stop a GWM Cannon’s DPF blocking, follow Nas’s rule of thumb: a steady run of about half an hour every week, or an hour every fortnight, so its self-clean (DPF burn) can finish. Suburban trips and site work never allow that, which is how a 2.0 or 2.4 Cannon blocks its filter while it still feels new. The H6, Jolion and Tank 300 turbo petrols build carbon on the intake valves instead. On the hybrids (H6 and Jolion Hybrid, Cannon Alpha Hybrid, Tank 300 Hybrid), the petrol engine seldom reaches full working temperature, so a hydrogen carbon clean is the prevention step.

If the DPF light keeps coming back, the engine light is on or the Cannon has gone into limp mode, book a time at our Kings Park workshop. We scan it free first, tell you what it needs, and quote before any work starts. That may be an on-car DPF clean, with the EGR and fuel side checked so it does not fill straight back up.

NAS is a Professional and knows his work I was told by mechanic he will open send exhaust for cleaning NAS professional performed at a very reasonable price Plus gave guidance to do 1 hour drive a fortnight to clear Very honest operator.

Ram Kishor · Google review

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

Do not just clear the light. If the DPF light comes back within days of being cleared, the filter is still loaded or something is still feeding it. Clearing the code does not clean anything.
Have the EGR side checked on a working Cannon. Towing and low-speed work coat the EGR circuit and intake. A coked intake means poorer combustion and more soot, which loads the filter faster.
Keep up the servicing. Oil changes at the interval in your handbook keep oil vapour from feeding intake deposits.
Do not rule out carbon on a new GWM. One that already feels tired may well be dirty rather than broken, so scan it before you assume a part has failed.

Book your GWM 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.

Get a Free Quote Call Nas — 0455 455 644