Steelers coach Mike Tomlin said Conner has an AC joint injury and is being evaluated. Tomlin expects to have an update on Conner at his Tuesday news conference.
Conner was injured near the two-minute warning after rushing for 145 yards on 23 carries and scoring a touchdown. With the return of fullback Roosevelt Nix, the Steelers' run game got going for 158 yards, averaging 5.4 yards per carry.
Conner had more than 100 yards of total offense against the Chargers before the bye week and followed up with 150 against the Dolphins.
"He came out hot early, and it really kind of sparked us as an offense," quarterback Mason Rudolph said of Conner. "Coach Tomlin has been talking all week about [making] those 10-yard runs, and we need more of them. We're making ourselves more of a complete offense. ... James did a good job. He's playing up there at the top of the competition of running backs in this league. He's a physical guy. He really provided us with a spark today."
Conner's health on a short week leading into Sunday's game against the Colts will be even more important because backup running back Benny Snell Jr., who had five carries for 13 yards, is being evaluated for a knee injury. Fellow backup Jaylen Samuels is coming back from arthroscopic knee surgery performed less than a month ago. Samuels was a full participant in practice leading up to Monday's game, but he was inactive.
That leaves the Steelers with former practice-squad member Trey Edmunds as the only healthy running back on the 53-man roster.