The Senators lead the best-of-seven Eastern Conference semifinal series 2-1, with Game 4 on Wednesday night at Scotiabank Place. Mike Comrie banked a shot off the end boards on a rush that came to Preissing on the right wing for a high blast.
It beat Devils goaltender Martin Brodeur to the glove side - a vulnerable spot for the future Hall of Fame goalie for much of these playoffs.
Jason Spezza added an empty-net goal, his fourth of the playoffs, with 56 seconds left in the game.
Ottawa outshot the Devils 34-35 and Ray Emery earned his second shutout of the playoffs.
A game in which both teams played solid team defence gave the red and black-clad sellout crowd of 19,636 little to shake their red pompoms through the opening two periods.
Brodeur may have got a break on an early whistle when Jason Spezza pushed in a puck he had trapped on the ice after stopping Daniel Alfredsson's backhand on a cruise through the crease 15:29 into the game.
But then Brodeur was at his best, robbing Alfredsson on a rebound during a power play at the start of the second frame and foiling Mike Fisher and Mike Comrie on back-to-back shots late in the period.
Midway through the second, smart forechecking put the Senators' defence in a generous mood for a short spell and Emery needed to be sharp to stop a Zach Parise blast from the slot, a Parise wrap-around attempt and another Parise chance when Joe Corvo put the puck on his stick in front of the Ottawa net.
Devils coach and general manager Lou Lamoriello had said at his meeting with the media Monday morning that "we are a low-scoring team. That is our philosophy," and his team played it to the letter but didn't get the goal it needed to win.
The Preissing goal was scored with the Comrie, Fisher and Peter Schaefer on the ice, a first in the series for the Sens' No. 2 trio.
The Devils were 0-5 while Ottawa was 0-4 with the man advantage.
The crowd got excited when Antoine Vermette poked in the puck at the end of the first period, but a replay showed time had expired. The Devils scored with 0.2 of a second left in the second period of Game 2 and Ottawa claimed the New Jersey timekeeper started the clock late.
Notes - Devils' rookie John Oduya, who played in round one vs. Tampa Bay, has been scratched for all three games against Ottawa. . . Ottawa's Patrick Eaves, who left Game 3 of the first round against Pittsburgh after a hard hit to the head, has yet to return but is still listed as day-to-day. . . Brodeur is the all-time leader in wins against Ottawa with 28.