An own-goal from Mat Sadler before half-time and a header from Franck Moussa gave the Sky Blues a two-goal lead, before late strikes from substitute Jamie Proctor and Andy Drury secured a deserved point for the Reds.
Whittingham was delighted that substitutes Proctor and Sergio Torres, whose cross was diverted in by Drury for the second, made a huge impact on the game.
"Credit where credit's due to the lads who came on," said Whittingham.
"One's scored for us and the other one made a run for the second. You need that when you come to places like this, you need players on the bench who can come one and make an impact.
"Coming here and getting a draw is a good result.
"In the second half we came out and really took the game to them, we were deservedly back in the game. When you come to Coventry they're a good side, it takes a bit of getting used to how they move the ball around.
"We've certainly got the heart. The positives outnumber the negatives. The biggest thing we've noticed since we've come here is the camaraderie of the team and the team spirit and the desire, they've shown it at Preston and they showed it here, in another really encouraging performance."
The Sky Blues dominated the first-half, and eventually opened the scoring on 40 minutes, after Andy Webster's header was diverted in by Sadler.
Moussa doubled the lead with eight minutes to go but it was the double substitution which changed the game in the 78th minute when Proctor and Torres came on for Gary Alexander and Josh Simpson.
Substitute Proctor headed in on 83 minutes, before Torres' cross was diverted in by Drury with three minutes left.
City manager Steven Pressley was left disappointed with his side failing to earn three points from a commanding position.
"I am disappointed after being 2-0 up with 10 minutes to go," said Pressley.
"I thought we were excellent in the first half and passed the ball really well especially when you consider that we had no recognised striker on the pitch.
"In the second half we didn't pass with the same kind of consistency and they came back into the game.
"The one point I made to the players was that despite the circumstances was that there is always a way to win a game and, at 2-0, I thought we had found a way.
"But one individual switched off after we went 2-0 up and didn't do their job from a throw-in. He has let his team-mates down and we can't afford to do that - especially after we worked so hard to get in a strong position."