What was found
HNL FLT 125 EN ROUTE HNL TO PHX. DURING CLIMB OUT FROM HNL, THE CABIN CREW REPORTED A LOUD NOISE, POSSIBLY COMING FROM THE DOOR. THE FLIGHT CREW REPORTED THAT THE AIRCRAFT WAS UNABLE TO PRESSURIZE, ALTHOUGH THERE NO EICAS MESSAGES OR OTHER INDICATIONS FROM THE AIRCRAFT TO INDICATE WHAT THE PROBLEM WAS. FLIGHT RETURNED TO HNL AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE LEFT ENGINE BVCU. OPERATIONALLY CHECKED THE PACKS AND INSPECTED THE L2 DOOR SEAL WHILE THE CABIN WAS PRESSURIZED. NO FAULTS WERE FOUND. OK FOR SERVICE.