Ingimarsson, 32, was rested by manager Brian McDermott for the midweek trip to take on Crystal Palace and saw his team-mates pick up a vital 3-1 win at Selhurst Park.
That was the Royals' fourth straight league win under McDermott and lifted them above Ipswich and out of the Championship relegation zone.
Striker Shane Long will be absent as he serves a four-game ban but replacement Simon Church will continue to lead the line after firing a brace at Palace.
Marek Matejovsky (abdomen) and Noel Hunt (knee) remain sidelined but Gylfi Sigurdsson made a return from a foot injury as a substitute at Selhurst Park and may come into the starting XI.
