One problem related to engine clicking and tapping noises has been reported for the 2012 Toyota Prius. The most recently reported issues are listed below.
The contact owns a 2012 Toyota Prius hybrid. The contact stated that the automatic startup engaged independently with a loud clunking noise. The vehicle was towed to an authorized dealer for diagnosis. The technician was unable to duplicate the problem. The vehicle was also diagnosed by a different dealer who refused to repair the vehicle. The manufacturer was notified of the problem. The vehicle had not been repaired. The approximate failure mileage was 32,775. . . Updated 02-28-14 the consumer stated the vehicle was traded in. Updated 03/19/2014.