The visitors - who had lost their last four matches - restored their fragile confidence by taking the lead in the eighth minute.
David Nugent played a cross-field ball to Graham Alexander and the skipper beat Michael Mifsud to the ball as he played in Chris Sedgwick. The former Rotherham midfielder raced half the length of the pitch to slot a fine angled shot beyond Andy Marshall.
And Coventry were rocked when their visitors doubled their lead in the 17th minute.
Nugent's misplaced shot was collected by Sedgwick and he dummied Jay Tabb to deliver a cross into the six-yard box for Nugent to beat Robert Page in the air as he headed home his 17th goal of the campaign.
Coventry were struggling to reach the form their fans have become accustomed to seeing since Iain Dowie took over. They showed their frustration as Stephen Hughes and Isaac Osbourne picked up yellow cards.
Callum Davidson tried his luck with a 30-yard shot as Preston continued to dominate the opening 45 minutes.
Dowie made a double substitution at the start of the second half with Leon McKenzie and Dele Adebola replacing Mifsud and Tabb and Preston also made a change with Liam Chilvers coming on for Kelvin Wilson.
But the change failed to make the desired impact as the visitors added a third goal in the 49th minute.
Davidson's ball into the box reached Brett Ormerod at the far post and the striker had plenty of time to rifle home a close-range shot.
Coventry's misery deepened when Marshall's attempted clearance bounced off Page and Ormerod reacted quickly to slam the loose ball into an empty net.