Ambrose, who signed for Palace on a free transfer in the summer, has scored all of his team's five goals in their last five games and tapped in an off-target cross-shot from Freddie Sears in the 28th minute before Leon Best replied right after half-time for Coventry.
Palace manager Warnock said: "I am pleased with a point. I felt we should have had a penalty in the first half and if we had gone in 2-0 up then I don't think they would have come back from that.
"Darren is in good form and the goal he scored today is one of the most difficult because it was about anticipation. Who else would be thinking that Freddie would hit his shot like that? But I think there is even more to come from him."
The Sky Blues have not won in seven games but their performance and point pleased manager Chris Coleman who handed a debut to defender Richard Wood after he joined on loan from Sheffield Wednesday in midweek.
City had a great chance to take the lead in the first minute when goalkeeper Julian Speroni made a hash of a routine backpass but Michael McIndoe was forced too wide to take advantage.
Ambrose cracked a fierce shot from 30 yards after seven minutes but it flew over before Keiren Westwood denied Neil Danns.
Palace were worthy of their lead when Ambrose scored from close range, but Coventry were much improved as they grabbed an equaliser at the start of the second half.
McIndoe crossed from the left and Best headed in his eighth goal of the season.
Coventry dominated the second period but were foiled in front of goal as Wood and Clinton Morrison saw chances go begging and Alan Lee almost headed into his own net.
"It was a tough game and I knew it would be," said Coleman.
"There was a lot of courage and a lot of spirit and the reason we didn't get three points wasn't a lack of effort, things are just not dropping for us.
"We have been playing square pegs in round holes and you can only do that for so many games.
"We had a lot of players back today and that showed but I want to see them play half a dozen games together, then you have a chance.
"I have told the strikers I want them to work harder for the team and they did that today."