Hyundai Santa Fe models equipped with navigation units may suddenly stop playing audio from all speakers. This includes sound from CD players, radio, navigation, satellite radio, and telephone calls. All other features may still function properly. This fault requires no part replacement, and is a software glitch that can be rectified by a 'hard reset'. To perform the hard reset, simply disconnect the vehicles negative battery terminal, wait 15 minutes, and reconnect the negative battery terminal.