As expected Dave Jones wielded the axe following the poor performance at Plymouth.
Tom Heaton, Paul Parry and Kevin McNaughton had slight injuries while Darren Purse and Eddie Johnson joined Tom Heaton on the bench.
Cardiff were pinned back in the opening stages but broke away and Michael Chopra lashed a shot just wide after eight minutes.
The Bluebirds took the lead with a superb tenth minute goal from Wayne Routledge.
A swift break down the middle and Chopra slid a pass down the left flank for Routledge, who outpaced the defence before slotting beyond Marcus Hahnemann in the visitors goal.
Three minutes later Chopra was through, but Hahnemann saved then it was Mark Kennedy denied by the American keeper as City kept up the pressure.
But Reading were back on level terms from a Cardiff corner in the 16th minute.
When the ball was cleared Miguel Comminges was beaten for speed down the left by Jimmy Kebe and when the ball was turned into the middle, Kevin Doyle was unmarked to sidefoot it into the net.
On the half hour Andre Bikey was red-carded following a challenge on Routledge.
Ten minutes later Chopra went down under a challenge from Hahnemann and Ross McCormack restored City's lead from the spot.
Reading equalised five minutes after the break when Stephen Hunt crossed and substitute Brynjar Gunnarsson struck a first-time volley into the net.
The visitors were now looking dangerous and for long periods the Bluebirds were unable to keep hold of the ball, despite Routledge working hard all across the field.
Eddie Johnson replaced Jay Bothroyd on the hour as City tried to change a game that was slowly drifting away after such a promising start.
McCormack made space before clipping a shot goalwards only for Hahnemann to turn it round the post, but that was a rare City attack as ten-man Reading continued to hold control until the final whistle.