Loan signing Tommy Black grabbed a point for the Bramall Lane side to end a disastrous run of the three successive league defeats.
Manager Neil Warnock, without eight senior players, drafted in Black from Crystal Palace earlier in the week.
And Black, on a month's loan, responded with stinging 30th minute header after Andy Morrell had snatched a 15th minute opener for the Sky Blues.
Peter Reid's side had escaped in the first minute after Steve Staunton conceded a free-kick on the left. Leigh Bromby's deep delivery was met by skipper Chris Morgan whose powerful header crashed against the bar.
Midfielder Michael Doyle was inches away with a curling free-kick inches off target.
Luke Steele foiled Alan Quinn diving at his feet to clutch the ball after the midfielder had linked cleverly Paul Shaw.
Coventry snatched the lead in the 15th minute, full-back Jon Harley failing to clear Louis Carey's cross, the ball fell nicely for Doyle, his sweeping centre was snapped up by the unmarked Morrell at the far post, who finished clinically from close range.
Stern John almost added a second minutes later with a stinging shot from 22 yards, the ball lashing into the sidenetting before the Midlands side had the ball in the net in the 29th minute.
Paddy Kenny's free-kick fell to Morrell 30 yards out, who chipped the ball over the keeper's head only for referee Graham Laws to disallow the goal.
United were back on level terms in the 30th minute, midfielder Michael Tonge finding space on the left to pick out Black who headed powerfully past Steele from six yards.
Morrell saw his low strike snapped up by Paddy Kenny, who foiled John after the Coventry striker twisted cleverly to fire in a low strike from 18 yards.
Black headed narrowly wide in the 50th minute and had a low strike from the edge of the area stopped on the line by Steele, before the Coventry keeper brought off a stunning save 13 minutes from time, blocking Shaw's strike from point-blank range.