The win was Preston's first win in four games and only a third in 11 games.
In the fifth minute, Billy Jones made the keeper palm the ball away and then Chris Sedgwick had a cross saved after quarter of an hour.
Coventry took the lead in the 17th minute when Jordan Henderson found Stephen Wright, who got behind Eddie Nolan and assisted with a low cross-shot to the far post which Clinton Morrison slid in to touch home.
Ross Wallace had a low left-wing cross which Jon Parkin shot but the keeper saved at the second attempt.
Morrison and Sedgwick had efforts saved with Republic of Ireland international Morrison having another snapshot saved low down.
Preston won a free-kick on the right wing and Wallace fired it across the face of goal and then Ben Turner beat Sean St Ledger to send a firm header into the roof of his own net for an own goal after 38 minutes.
St Ledger squared to Stephen Elliott and he had a shot saved and Wallace had another effort saved before, in first-half added time, Marcus Hall crossed to Freddy Eastwood and he curled a right-foot shot from the edge of the box against the outside of the far post.
Sedgwick had a cross saved and David Bell had a left-wing corner saved at the start of the second half.
Parkin scored his ninth goal of the season in the 72nd minute when Kieran Westwood could only clear a free-kick to Wallace and he sent the ball down the middle to the big striker, who went around the keeper before hitting a low shot into the middle of the net.
Substitute Neil Mellor had a shot saved and Darren Carter found Simon Whaley, who shot from the edge of the box and brought a save from the Coventry keeper.
In the first minute of added time, St Ledger had another effort saved as Preston confidently played out time for a play-off boosting win.