The action relates to vehicles fitted with a 2.8-litre turbo-diesel engine.
Toyota Australia is facing a class action lawsuit over issues with the Diesel Particulate Filters (DPF) in 2015-18 HiLux, Prado and Fortuner vehicles powered by the 2.8-litre turbo-diesel engine.
According to the legal firm considering the claim, its clients have experienced "increased fuel consumption and a loss of power of the vehicle" because "hard deposits accumulating on the DPF oxidisation catalyst" stop it reaching the necessary temperature.
The claim says the DPF may be defective because the HiLux, Fortuner and Prado don't burn particulate matter in normal urban conditions, where many owners spend time, creating particulate matter buildup, DPF blockage, foul-smelling emissions from the exhaust, increased fuel use, and greater wear and tear on the engine.
It acknowledges Toyota contacted owners offering to clean or replace the DPF in affected vehicles, and retro-fit a manual regeneration switch, but says some owners have been dealing with the issues for a number of years, causing "unnecessary inconvenience and expense".
Earlier this year, the company made a manual regeneration switch standard fit on the vehicles included in this recall.
At the moment, the law firm is investigating possible contraventions of Australian Consumer Law (ACL) regarding "misleading and deceptive conduct" and "omissions equating to misleading and deceptive conduct".
A potential claim would encompass any repairs that weren't covered under warranty, a loss of income for tradies with vehicles that were taken off the road by the issue, compensation for any measurable increase in fuel consumption or loss of power, and coverage for any excessive depreciation because of the problem.
In a statement, Toyota Australia said it "launched the latest in a series of initiatives, a customer service campaign, to resolve the potential DPF issue" in October.
"All customers with potentially affected vehicles have been, or are in the process of being, contacted by letter and are requested to make contact with their closest/preferred Toyota dealer," the company said.
"Toyota dealers will reprogram the engine control module, ensure the DPF has been regenerated and conduct a smoke test. If the smoke test is negative, the DPF will be replaced. All inspection work and replacement, if required, will be completed free of charge to the customer.”