The fault, which also affects some of its Lexus models, could see engines stalling while being driven. The company has not yet started a global recall.
The warning is the latest problem to hit the world’s largest carmaker, which has recalled more than 10 million vehicles globally.
Earlier this month, Toyota began rolling out its “Your Toyota is My Toyota” advertising campaign, which features real employees championing the marque following its global recall crisis.
The campaign includes a TV ad and full-page press ads fronted by staff from Toyota Manufacturing UK, promising to “pick up imperfections that are smaller than a human hair.”
The ad stresses: “There’s no better method for ensuring the perfect panel than having that personal touch.”
Worries about further reputational damage and the costs of a potential recall pushed Toyota shares down by more than 2% as news emerged this morning.