In the wake of our recent six-vehicle comparison test in outback South Australia during which the HiLux Rugged X test vehicle dropped into limp home mode four times, Toyota Australia has admitted a design flaw with the air inlet system of the 2.8-litre turbo-diesel engine and that a fix has been requested from Japan.

And yep, the same 2.8-litre 1GD-FTV engine fitted to the Fortuner and Prado has the same problem too!

Toyota Australia says that if feasible, it will retrofit the redesign to existing vehicles for no charge. But at least for now – and maybe always – you are going to have be extra vigilant when you drive off-road and clean out your air filter more often.

We get an air filter expert on the case. Read his verdict here.

The design flaw allows dust to leak past the air filter and corrupt the readings of the mass air flow sensor, which measures the rate of air entering the engine. The engine control unit (ECU) use the reading to determine the correct fuel ratio.

The corrupted data prompts the engine to go into limp home mode, a potentially dangerous outcome in the wrong situation, such as when overtaking.

Safety systems such as stability and traction control are also shut off and the owner is urged to take the vehicle to a Toyota dealer immediately.

The engine in our test HiLux Rugged X went into limp home mode four times without warning. It was temporarily fixed each time by disconnecting and reconnecting the battery.

Do the mods improve the HiLux Rugged X off-road? Absolutely.
When dust gets past the filter, it corrupts the MAF sensor reading. Next stop, engine.

“The dust that makes its way through the filter is very fine and typically less than 5 microns in size. What can occur is that these very fine particles attach themselves to the sensor electrostatically. It is not an issue of the dust finding their way into any internal components of the MAF sensor,” the Toyota spokesperson said.

Toyota played down any chance of engine damage from the issue.

“The dust particle size that passes through the air intake system can become statically charged and adhere to the MAF sensor. The size of these particles is around two microns. In general, this type of very fine dust is not known to cause engine damage.”

We’re not so sure about that, so will follow up with some experts on their opinion.

None of the other five dual-cab turbo-diesel dual-cab utes from other brands that participated in the testing program had the same issue.

Toyota also rejected the suggestion the issue should be the subject of a mandatory safety recall.

“As the vehicle is subject to reduced engine power (‘limp mode’) and can continue to be operated safely, it is not a safety related item that would require a recall,” the spokesman stated.

The Toyota HiLux was Australia's best selling vehicle in 2017, and a vast majority of them have this problem.
The Toyota HiLux was Australia’s best selling vehicle in 2017, and a vast majority of them have this problem.

While Toyota Australia is only publicly acknowledging the issue in the wake of our test, it issued service bulletins to dealers as far back as March 2017 advising them that industry conditions the engine required air filter cleaning more often that recommended in the service manual. The bulletin also recommends an additional two-minute procedure to blow compressed air past the MAF sensor.

Owners are also being made aware of the issue and being advised to clean the filter more often.

“It’s important that the air filter is checked more regularly in extremely dusty conditions … it’s an easy fix to have dust blown out [to clean the sensor].”

It has also been found that an air snorkel, such as fitted to the Rugged X we tested, can exacerbate the problem. Toyota says that issue can be reduced by turning the intake rearward, a recommendation it makes in the Rugged X owner’s manual.

Toyota makes a big deal about how important Australia is as a test ground for its 4x4s and the problem has been sent back up the line to Toyota HQ for a fix.

“We have provided details of the experiences in the field in Australia to our head office in Japan and they will be making design changes to improve the performance of the air intake in extremely dusty conditions at the earliest possible opportunity,” the spokesman confirmed.

Now without a 4.0 litre V6 option, the Prado (and Fortuner) only comes with the 2.8 litre diesel.
Now without a 4.0-litre V6 option, the Prado (and Fortuner) only comes with the 2.8-litre diesel.

The redesigned air intake’s introduction timing is unknown.

“Any change to the intake system will affect emissions and homologation and therefore will require extensive retesting. At this stage we believe it will not make it in time for the next technical change but we will endeavour to expedite this so it is implemented at the earliest production opportunity.

“We have requested that any changes to the air intake or other related systems be made available also to vehicles already in the field, however, as the design is not yet complete, it is too early to say whether this will be possible.”

The fault is a dent in Toyota’s hard-earned reputation for quality and reliability and a knock for the HiLux, which has been Australia’s top-selling vehicle for the last two years.