The Eagles academy graduate equalised Aron Gunnarsson's opener just ten minutes after coming on as a second-half substitute to deny the Sky Blues what would have been a richly-deserved three points.
Coventry totally dominated the opening period - first Clint Morrison - on his first return to Selhurst Park since his summer departure - prodded just wide after Gunnarsson's cross-cum-shot in the second minute.
The former Palace striker again went close in the 20th minute before Julian Speroni brilliantly tipped Freddy Eastwood's fierce strike from the edge of the box round the post.
And the away side were rewarded for their bright opening in the 31st minute when Gunnarsson rose above Matt Lawrence to head Issac Osbourne's cross past Speroni.
Eagles dangerman Victor Moses registered the home side's first real effort in the 37th minute with a scuffed shot that rolled harmlessly wide before Neil Danns watched his goalbound effort cleared by Morrison.
Palace went agonisingly close to snatching an undeserved leveller four minutes before the break but City keeper Keiren Westwood somehow clawed out Anthony Stokes' stinging long-range effort.
Coventry continued to apply the pressure after the break. Firstly, Gunnarsson missed a golden chance in the 62nd minute after latching onto Guillaume Beuzelin's raking pass before having another effort cleared off the line by Lee Hills moments later.
And City were made to pay for their wastefulness after debutant Cadogan capitalised on Ben Turner's mistake, rounding Westwood before slotting into an empty net in the 71st minute.
The goal ignited Palace with Shaun Derry and Cadogan both missing chances in the closing stages as it ended all-square.