The National Highway Traffic Safety Administration recently began an investigation of about 120,000 Tesla Model Y models after the agency received two reports that the steering wheel of Tesla vehicles fell off during driving.。According to the agency's documents, both of the problem cars lacked a bolt to fix the steering wheel to the steering column when they were handed over to customers, but the documents did not indicate whether this quality problem caused the accident or personal injury。Tesla shares down 3 as of day's close.04% to $182 per share。