Johnson caught a 13-yard pass in the second quarter and was holding the back of his right leg near the knee after he fell to the ground. He pulled up at the end of the play, but was not hit.
He remained on the field and was looked at by trainers before gingerly walking off on his own power.
He then walked to the locker room with members of the training staff.
The team says his return is questionable.
Running back Ben Tate also left a groin injury.
Tate had two carries for 20 yards before the injury and the Texans say his return is questionable.
Tate has led the Texans in rushing this season with Arian Foster out with an injured left hamstring. He had rushed for more than 100 yards in two of Houston three games entering Sunday.
Foster returned on Sunday and started against the Steelers.