Sean St Ledger hit a rare goal to lift Preston out of the drop zone with this scrappy win over fellow strugglers City.
The home side opened the scoring when Darren Carter worked a short corner with Paul McKenna before whipping a cross to the back post where St Ledger was lurking.
The defender headed home from six yards for only his second ever goal for the club in 69 games.
Boss Alan Irvine said: "It is a great result - a massive result.
"There is still a long way to go and a lot of hard work to do.
"We still need another seven wins to be sure of safety and I would like to get them as quickly as possible - but I think the battle will go all the way."
Coventry had a couple of half-chances but were often reduced to shooting from the edge of the box.
The closest the visitors came to scoring in the first half was when Liam Chilvers almost turned Michael Doyle's low cross into his own net.
Preston really should have gone into the break with a two-goal lead after Chris Brown played Simon Whaley in with a reverse pass, but keeper Dimi Konstantopoulos did well to pull off a low save.
City boss boss Iain Dowie said: "It is a game we should never have lost, really. But we were poor in both boxes.
"The worst we should have got out of this game was a 0-0."