Officials from General Motors Co. and the government believed the fires were caused by coolant leaking from damaged plastic casing around the batteries after side-impact test crashes. At the time, they said there were no real-world fires in any Volts.Still, the fires tarnished the Volt's reputation and cut into sales. Recently, though, sales have recovered. Sales are up about 3 percent this year, with GM selling about 17,000 Volts through September. Earlier this year, Boeing Co.'s worldwide fleet of 787s was grounded because lithium-ion batteries overheated or caught fire. Flights resumed four months later after a revamped battery system was installed. Under normal circumstances, investigators from NHTSA, the government's auto safety watchdog, would travel to Washington state to investigate the Tesla crash. But with the partial government shutdown, NHTSA's field investigations have been suspended. ___ Follow Mike Baker at https://twitter.com/MikeBakerAP .