With three games remaining, the Bluebirds are now all but certain of a place in the top six due to their seven-point advantage over seventh-placed Blackpool, although one more victory will make sure.
Resurgent Reading's chances, however, remain less clear as they lie nine points adrift but have two games in hand over all of their rivals.
Brian McDermott's side really need victories if they are to realise their play-off dream and it was they who came closest on a sunny afternoon in Cardiff, Wales international Simon Church finding the woodwork in the 65th minute with almost his first touch having come off the bench.
But both sides enjoyed half-chances and spells of pressure and a point apiece proved about the right result.
The hosts started on the front foot with a couple of corners and efforts from Jay Bothroyd and Stephen McPhail inside the opening six minutes.
Yet Reading weathered the early pressure and soon gained a foothold on proceedings, with passing play from both sides contributing to a encounter that was pleasing the purists among the 21,248 in attendance at the Cardiff City Stadium.
However, with both sides cancelling each other out in the middle of the park there was a significant lack of goalmouth action in either penalty area.
Peter Whittingham put a half-chance wide after 26 minutes, connecting with Bothroyd's low cross at the near post after he had been sent clear down the right by Michael Chopra.
The chances of a breakthrough started to diminish further as the half wore on with the game becoming somewhat scrappy.
And with Royals keeper Adam Federici saving well from Kelvin Etuhu's low drive after his strong run shortly before the break, a low-key opening 45 minutes unsurprisingly ended goalless.
Chopra was replaced by Ross McCormack at the break but it was Reading who threatened first after proceedings had got back under way, captain Brian Howard firing narrowly over the angle of post and bar.
The chance promised to be a false dawn as the second half settled into a similar rhythm as the first but the pace soon picked up and opportunities started to appear at both ends.
Reading were posing the bigger threat with Gylfi Sigurdsson and Jimmy Kebe seeing goalbound shots blocked before the former tested Bluebirds keeper David Marshall with a set-piece from 30 yards.
As the game opened up, Bothroyd forced Federici to tip his effort around a post before substitute Church came closest to breaking the deadlock for the visitors.
The lively Sigurdsson whipped a corner into the area and Church saw his close-range header bounce off the frame of the goal.
The points were there for the taking as the game entered the final 20 minutes and Reading looked the most likely to claim them as they pressed matters in the final third.
But it was not to be as Cardiff extended their unbeaten run to eight while Reading have now lost just two of their last 15 league games.