After winning eight of nine, the Pacers have lost two in a row.
Wall produced his second-largest point total of the season behind the 47 he managed against Memphis late last month. He hit 16-of-25 from the field and was backed up by 15 points off the bench from Kevin Seraphin.
The Wizards limited Indiana to 3-of-20 from 3-point range.
Roy Hibbert scored 25 points and grabbed 10 rebounds for the Pacers, who fell a game below the .500 mark in road games this year.