The hosts dominated the ball in the first half, having nine shots, with three of those on target.
Early on, Matt Grimes made a burst through midfield and let fly with a dangerous right-footed shot which flew narrowly past the right-hand post.
Tatsuhiro Sakamoto then had a great chance to open the scoring just after the half-hour mark, shooting low towards the bottom right-hand corner but U’s keeper Jamie Cumming made a brilliant save.
Oxford’s best chance of the half came when Christ Makosso’s super pass found Przemysław Płacheta, but the winger’s attempt on goal went behind for a goal-kick.
Oxford’s Cumming was thanked again by his team-mates just after the hour mark when he denied Romain Esse with a great save after the Coventry man curled a shot towards the bottom corner from outside the box.
The U’s were then reduced to 10 men as substitute Will Lankshear was shown his second yellow card having come on just 20 minutes earlier
The striker barged into Coventry’s Joel Latibeaudiere in an attempt to break in behind and the referee gave him his marching orders.
Frank Lampard’s side pushed late on to break the deadlock, but the Oxford backline held firm and the points were shared.