City inspectors later reported that there were no smoke detectors on the ceilings or walls.
If convicted of the misdemeanor charges, Aguilar faces up to six months in jail, plus a $1,000 fine for each offense.
Killed in the fire were Uriel Estrada, 41; his wife Maria Estrada, 40; and their children -- Isabel, 12, and Alejandro, 7. All were pronounced dead at the hospital.
Investigators believe the fire started in the home's living-dining area, adjacent to where the 12-year-old girl was sleeping, on the first floor.
The fire spread quickly and became concentrated on the second story of the building, which was not used as living space, officials said. Smoke and flames alerted witnesses, who called 911 about 4:30 a.m.
L.A. City Atty.
City records indicate that the owner was authorized to convert the barn into living space. However, the property's permits do not allow for it to include a kitchen or be used as permanent residential housing for longer than 30 days, said Luke Zamperini, a spokesman for the Los Angeles Department of Building and Safety.
According to descriptions by fire officials, the home included a kitchen area with a stove, refrigerator and sink.
At the time of the blaze, Brian Weinberger, an attorney for property owner Aguilar, said his client was "very distraught over this tragic occurrence" and was fully cooperating with arson investigators.
He also told The Times shortly after the blaze that his client had provided smoke detectors at the residence "all along" and that new smoke detector units "were provided" when the family moved in about six weeks ago.
But an arson investigator said a sweep of the burned-out remains did not yield any smoke detectors, and that no mounting brackets consistent with installed devices were found.
The building is one of two structures on the two-acre lot.
Weinberger has also denied that Aguilar made any "substantial changes or do any construction" on the property after purchasing it.
"If there was a kitchen there, then it was there on the property when they purchased it."