MajorCommonEngine

Toyota Voxy: 1AZ-FSE D-4 Fuel Dilution of Engine Oil

1AZ-FSE D-4 Fuel Dilution of Engine Oil is a common engine fault on the Toyota Voxy on the 2001–2007 cars, and we rate it major. Putting it right costs ≈A$140 to ≈A$550 at independent workshop rates, shown as an approximate guide in Australian dollars. 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 32 documented faults on the Toyota Voxy.

Vehicle: Toyota Voxy
Engine: 1AZ-FSE
Years: 2001–2007
Fuel: petrol
System: Engine

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

All Toyota Voxy faults32 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph for this fault yet. We would rather show none than show a picture of something else.

What goes wrong

During cold starts the 1AZ-FSE D-4 engine enriches the fuel mixture and retards injection timing to aid warm-up. Unburned fuel puddles on cold cylinder walls and migrates past piston rings into the sump, diluting engine oil with petrol. Repeated short cold trips compound the effect, reducing oil viscosity well below its rated grade and accelerating bearing and piston wear. The problem is most severe in vehicles used predominantly for short urban journeys.

What you would notice

Petrol smell detectable on the oil dipstick
Oil level rising above the maximum mark without any top-ups
Thin or watery oil texture on the dipstick
Increased engine wear if not addressed by shortened service intervals

How to check it

Where to look. Engine crankcase and oil sump

Pull the dipstick and smell for fuel contamination — oil should smell like oil, not petrol.
Check whether the oil level reads above maximum without any top-ups having been performed.
Review service records for oil change intervals; vehicles used for short trips should show intervals shorter than 5,000 km.
Cold-start a known history vehicle and check for excessive white or rich exhaust smoke.

What it costs to put right

≈A$140 to ≈A$550 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, 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

“What was the typical journey length this vehicle was used for daily?”
“Were oil changes done more frequently than the factory-specified interval?”

Now check the Toyota Voxy 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 still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

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.

Toyota Voxy buyer questions

Is 1az-fse d-4 fuel dilution of engine oil serious on a Toyota Voxy?

We rate it major and common on the Toyota Voxy. During cold starts the 1AZ-FSE D-4 engine enriches the fuel mixture and retards injection timing to aid warm-up. Unburned fuel puddles on cold cylinder walls and migrates past piston rings into the sump, diluting engine oil with petrol. Repeated short cold trips compound the effect, reducing oil viscosity well below its rated grade and accelerating bearing and piston wear. The problem is most severe in vehicles used predominantly for short urban journeys.

How much does it cost to fix on a Toyota Voxy?

≈A$140 to ≈A$550 at independent workshop rates, shown as an approximate guide in Australian dollars. 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 Toyota Voxy years are affected?

Our research records this fault on the 2001–2007 Toyota Voxy. 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?

Pull the dipstick and smell for fuel contamination — oil should smell like oil, not petrol. Check whether the oil level reads above maximum without any top-ups having been performed. Review service records for oil change intervals; vehicles used for short trips should show intervals shorter than 5,000 km. Cold-start a known history vehicle and check for excessive white or rich exhaust smoke. Look here: Engine crankcase and oil sump