The Gulls had made it through to round four with a superb 1-0 victory at home to Championship Blackpool in the third round, having previously disposed of Oxford United, Evesham and Chipstead.
Visiting Coventry eased past Kidderminster Harriers in round three, but Chris Coleman's side were soon under pressure at Plainmoor.
However, 11 minutes in Kevin Nicholson came to Torquay's rescue as he was on hand to turn a Daniel Fox effort off the goal-line, after Fox had combined well with Leon McKenzie.
Seven minutes later the home side went close, as Nicholson's free-kick found Tim Sills unmarked in the area, but the striker failed to direct his header on target.
Just before the half-hour mark the Gulls carved out another chance, but Matt Green's left-foot shot went the wrong side of an upright.
Right on half-time the visitors were forced into a change in defence, with Aron Gunnarsson being replaced by Elliott Ward.
Straight after the restart Torquay had shouts for a penalty when Roscoe D'Sane went down in the area, but referee Mr Friend waved the claims away.
City keeper Keiren Westwood then had to palm away a Nicholson corner, before he made a superb low save to deny the dangerous Green after the home forward broke through.
D'Sane fired a shot over the crossbar from close to the penalty spot as Torquay turned the screw, with Wayne Carlisle and Green also having efforts off-target.
Midway through the second half McKenzie lifted a shot over the top as Coventry finally responded, before Sills headed too high from a Green cross.
Nicky Wroe was off-target with a couple of efforts and Chris Hargreaves went close as the Gulls were unlucky not to clinch a deserved victory.
Even their hopes of a replay then disappeared as substitute Ward headed home a deep Fox corner with just three minutes left to play to earn Coventry a place in the fifth round.