Both teams had chances to win it throughout but poor finishing in front of goal was the story of the day, leaving Northampton 19th and Oxford 15th in the battle to beat relegation.
Chris Long missed two chances inside the first 18 minutes for Northampton, skewing over from 18 yards and then side-footing wide after good play from Gboly Ariyibi, before Richardinho’s goalbound shot was blocked on the line by Brendan Moloney.
Isaac Buckley-Ricketts clipped the top of the crossbar as Oxford grew into the game with Ryan Ledson also whipping a long-range effort narrowly wide.
Long went close for a third time in the second half when blazing over from inside the box before Matt Crooks and Sam Hoskins were unable to force home a goalmouth scramble.
The best opening of the entire game fell late on to Wes Thomas, who should have won it for Oxford but he headed wide from six yards.
Morecambe have no fresh injury concerns ahead of Tuesday's Sky Bet League Two home clash with Colchester.