Former Limerick defender O’Connor was handed a Leeds debut with United having a raft of defenders injured, including captain Liam Cooper and Everton loanee Matthew Pennington.
Twenty-year-old O’Connor produced a steady display alongside Swedish international Pontus Jansson at centre-back but Leeds looked to be staring at another defeat when Paddy McNair fired the second-bottom Black Cats into the lead three minutes after the break from Lynden Gooch’s clever flick.
Leeds equalised through a fine strike from Spaniard Pablo Hernandez 18 minutes from time but were unable to net a winner with Samu Saiz’s late free-kick hitting the post before captain Gaetano Berardi was shown a straight red card for a late and high two-footed tackle on Callum McManaman in the 90th minute.
Berardi is heading for a five-game ban following his third red card of the season as part of a hugely disappointing campaign for the 13th-placed Whites, who only missed out on a play-offs by one place and five points last term.
Head coach Paul Heckingbottom’s side again squandered plenty of chances with Ronaldo Vieira also hitting the post in the first half in which Hernandez blazed a good effort just wide.
But 21-year-old goalkeeper Bailey Peacock-Farrell equally kept the Whites in the game with a string of impressive saves.
Hernandez’s efforts aside, the displays of youngsters Peacock-Farrell and O’Connor were the main positives for Leeds and O’Connor has set his sights on keeping his place in the side.
“I have come from back home in Ireland where it’s a fairly physical league anyway,” said O’Connor.
“I have played nearly 50 games up against men who like to throw themselves about so I kind of knew that if it was going to go like that I would be able to deal with it and I think I have done okay in that regard.
“I have played for the Under-23s for a bit now so it’s up to me now to try and hold on to the jersey.”
Leeds are destined for a mid-table finish, sitting 12 points off the play-offs and 17 clear of the drop zone with five games left.
Head coach Heckingbottom said: “After going behind you can’t be satisfied with a draw but I do give the players credit for coming back.”
Leeds United: Peacock-Farrell, Dallas, Jansson, O’Connor, Berardi, Phillips (Roofe 65), Vieira, Alioski, Hernandez, Saiz (Anita 90), Lasogga (Ekuban 79). Unused substitutes: Lonergan, Pearce, Nicell, Grot.
Sunderland: Camp, Love, Kone, O’Shea, Wilson, Cattermole (LuaLua 90), McNair, Honeyman (Ejaria 84), Gooch, Fletcher, McGeady (McManaman 89). Unused substitutes: Steele, Matthews, Asoro, Clarke-Salter.
Referee: J Simpson (Lancashire).