481,824 vehicles recalled in Japan over faulty Denso fuel pumps, bringing total to 4.3 million vehicles

Four Japanese carmakers and two motorcycle manufacturers have notified the country’s transport ministry that they have issued a recall for 481,824 vehicles over a faulty fuel pump manufactured by supplier Denso. The latest set of recalls take the cumulative number of vehicles to be recalled due to the issue to some 4.3 million vehicles. The component manufacturer said it has been working with carmakers on the matter since March 2020.

The recall involves eight models from Subaru (229,800 units), 15 from Mazda (146,700 units), two from Suzuki (64,900 units), three from Mitsubishi (36,700 units) and three motorcycle models from Honda (3,400 units), Jiji Press reports.

Affected models include the Subaru XV, Mazda Demio, Suzuki XBee, Mitsubishi Eclipse Cross and Honda Gold Wing, made between June 2017 and December 2023. Additionally, motorcycle maker Yamaha Motor said it will also replace pumps shipped as replacement parts and installed in vehicles.

Suzuki said it will issue a recall of 18,000 units outside Japan, but Subaru, Mazda, Honda, Mitsubishi and Yamaha aren’t planning to recall vehicles in other countries.

Meanwhile, the transport ministry said Denso has identified the major cause behind the defective fuel pumps, as Asahi Shimbun reoorts. Company officials said a new mold that was used to create a plastic impeller for the fuel pump led to a decrease in the density of the plastic, which allowed the part to bloat, eventually causing the pump to stop working.

Another factor was the environment in which the part was stored before its installation into a vehicle. In July 2023, a minivan made by Honda that was fitted with the defective fuel pump was involved in an accident in Japan, leading to the first known fatality stemming from the defect.

Honda personnel who analysed the part said storing the impellers with low plastic density in a warehouse for long periods before installation in a vehicle led to the drying of the part surface, which resulted in small cracks developing in the impeller as the plastic contracted.

Transport ministry officials said the low density of plastic in the impeller allowed fuel to seep into the part, causing the part to bloat. Bloated enough, it would come in contact with the surrounding pump case, resulting in the impeller not being able to spin. In a worst-case scenario when fuel is prevented from reaching the engine, vehicles will abruptly come to a stop.

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