What was found
PHX - FLT1505 - AFTER LANDING IN PHX, CREW STARTED APU DURING TAXI-IN TO GATE. AFTER APU STABILIZED, CREW SELECTED APU BLEED AND REPORTED SMOKE CAME INTO THE CABIN AND FLIGHT DECK. ADJACENT AIRCRAFT REPORTED EXCESSIVE SMOKE COMING FROM APU TAILPIPE AREA. CREW MANUALLY BLEW THE APU FIRE BOTTLE AND SHUT DOWN THE APU. AIRCRAFT TAXIED TO THE GATE WITHOUT FURTHER INCIDENT WHERE THE PASSENGERS DEPLANED NORMALLY. FIRE EQUIPMENT DID FOLLOW THE AIRCRAFT TO THE GATE. MAINTENANCE PLACED THE APU ON MEL 49-1001 AND THE APU FIRE EXTINGUISHING SYSTEM ON MEL 26-2200.