As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A POP WAS HEARD WHILE ON APPROACH TO EWR AT 4,000 FEET. THE GEAR WAS LOWERED, BUT THE GEAR DOOR REMAINED OPEN. THE AIRCRAFT LANDED AT EWR WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED THE MLG SELECTOR /BYPASS VALVE IAW MM 32-31-03, PAGE 401. LEAK AND OPERATIONAL CHECKS WERE GOOD.