There was little happening until Ian Morris netted in the 18th minute. He picked up the ball inside his own half, turned past Adam Bolder and advanced before leaving Lee Grant flat-footed with a spectacular drive into the bottom corner.
Franck Songo’o then hit a low drive that went wide before he saw a shot blocked on the line by Izzy Iriekpen.
The visitors levelled when Ben Sahar pounced on 49 minutes.
Deon Burton’s free-kick was cleared by the Scunthorpe wall and Jermaine Johnson’s follow-up was going wide of the post until Sahar stuck out a leg to divert the ball past Joe Murphy.
United’s Grant McCann saw his crossed free-kick cannon back off the woodwork after a touch from Grant on the hour.