Gentry, 67, told ESPN's Adrian Wojnarowski that he's largely asymptomatic except for a scratchy throat. He needs two negative tests 24 hours apart to return to the bench.
The Kings canceled their morning shootaround and were testing to discover whether there are more positive tests, sources told Wojnarowski.
Assistant Doug Christie filled in for Gentry as acting head coach against the Wizards.
Gentry took over as the Kings' interim head coach last month when Luke Walton was fired.
The Kings (11-17) have gone 5-6 in the 11 games under Gentry but have lost their past three games.