The club were concerned the defenceman - so often the heartbeat of the side - had fractured his left ankle in the win over Cardiff Devils, at Sheffield Arena, last Saturday.
But tests have shown it is sprain rather than a break.
The 30-year-old skater won't be available for this weekend's matches with Milton Keynes Lightning (home) and Belfast Giants (away.)
And he is rated 50-50 for the following weekend, when Steelers wrap up their league season, against Lightning, again.
O'Connor is a key asset at both ends of the ice.
Offensively, he has averaged a point a game over the last five outings and is third top points scorer with eight goals and 33 assists.
Only playmaking centre Evan McGrath has scored more assists, and he has iced in 14 more games.