Mow's 2005 silver GMC Envoy with California license plate number 5LJV959 is also missing.
DeMars said that in February, Mow was hospitalized for a week after losing consciousness, but doctors were not able to diagnose his illness.
"We're worried he had another episode while he was driving and could have had an accident," said DeMars.
Mow works as a general contractor on home renovations and lives alone on Boundary Street. He is Asian, about 5 feet 11 inches tall and weighs 250 pounds.
Anyone with information about his whereabouts is asked to call the San Diego Police Department at (619) 531-2277.
CNS contributed to this report.
