Toyota affiliate Daihatsu rigged part of the door in side-collision safety tests carried out for some 88,000 small cars made and sold under the Toyota brand, the companies said on Friday.
They said the door trim on the affected vehicles had been modified with a "notch" to minimize the risk in testing that the door interior could break with a sharp edge and cause injury to an occupant when the side airbag deployed in an accident.
The modification for testing was not part of the production vehicle, the companies said.