Residents of Kalihi Valley said they could barely hear the emergency sirens go off last night.
"I heard it off in the distance after my wife had gone in the house, and I was out in my house very very faintly. A sound of like... you are doing an ear test where you could barely hear it," said Melvin Smith, a resident of Kalihi.
"We live kind of in the valley, I didn't hear anything the only way I knew was because of Facebook," said resident Joey Pabalan.
Civil Defense officials said there were reports of faint-sounding sirens in about five areas in Oahu.
"Folks that did not hear sirens or reported faint sirens; it could have possibly been a malfunction with the turning mechanism," said Shelly Kunishige with the Civil Defense office.
Also, the Department of Emergency Management said only 75 percent of the sirens went off when they were initially activated.
"Not all of the sirens were sounding, so we immediately tried to reactivate the sirens," said Peter Hirai with Department of Emergency Management.
But civil defense officials said problems like that should be solved with the new siren activation system that is a part of the statewide Siren Modernization Project.
The system will support two-way communications for troubleshooting.
Kunishige said, "Receiving the data immediately if a siren had sounded or not; also having a backup method so that new system does both satellite and cellular activation."
All of the more than 180 sirens on Oahu will be upgraded. However, civil defense officials encourage residents to get other warning systems like a NOAA weather radio or to sign up for local emergency notifications.