Japan's top four carmakers are recalling a total of 3.4 million cars over a defect in passenger airbags.Toyota, which is recalling 1.73 million cars, said the vehicles had a defective part which "could cause the airbag inflator to rupture and deploy the airbag abnormally in a crash".Globally, Honda is recalling 1.13 million cars, Nissan almost 500,000 and Mazda 45,000.In the UK, Toyota, Nissan and Honda are all recalling certain models.The cars were sold in the years 2000-04, and the firms said the defective part was supplied by parts maker Takata Corp.UK models affected include:76,000 Toyota vehicles, including Corolla and Yaris, 60,000 Nissans, including X-Trail, Patrol, Almera, Almera Tino, Terrano II and Navara and 15,400 Hondas, most of them CRVs, but including 400 Jazz and Civic models.Nissan advised UK customers to contact garages where the cars were bought or call 01923 899334.Global car giants are usually quick to recall vehicles for inspection and repair as soon as they are aware of a fault.These generally tend to be minor and it is rare that they are linked to accidents or fatalities.Shares in Takata fell 9% to 1,819 yen on the Tokyo Stock Exchange on Thursday.Free replacement Ryo Sakai, a spokesperson for Toyota, told the BBC that the firm had received reports of five separate incidents of the airbag inflator being ruptured.Two of these incidents took place in Japan and three in the US, Mr Sakai said.However, he added that there had been no injuries as a result of the incidents.Meanwhile, Honda, Nissan and Mazda said that there had been no incidents involving their cars.All four carmakers have said that they will replace the defective parts for free."We are conducting a voluntary safety recall to address this issue and replace the front passenger bag inflator," a spokesperson for Nissan told the BBC."We plan to notify the customers over the next 30 days," he added.