The first threat of the game fell to Adebayo Akinfenwa, who nodded Karl Hawley's cross wide of David Martin's post.
After Danny Jackman had blasted a free-kick over the bar for Town, City mustered their first chance on 18 minutes when Lloyd Dyer crossed and Matt Oakley fired in a 12-yard shot which flew just wide of the frame.
Dyer continued to prosper down City's left flank, but neither Matty Fryatt or Steve Howard could take advantage when the winger got in another good cross.
The Cobblers bossed the game when Abdul Osman crossed for Ryan Gilligan to head just over.
The Foxes were gifted a chance within moments of the re-start when a weak back pass by Jackman was spotted by Fryatt, who volleyed the loose ball just wide.
Northampton were foiled when Akinfenwa's close-range shot was blocked by Joe Mattock after Giles Coke had flicked on a Jackman corner.
Leicester went close on 65 minutes when Oakley put Dyer clean through.
Frank Fielding managed to block the winger's shot, with Fryatt firing wide after Dyer had pulled back the loose ball.
The clearest of chances fell to Fryatt on 75 minutes when Andy King's pass left him one-to-one with the keeper.
The striker was odds on to score as he bore down on goal, but he was left to bury his head in his hands after a tame shot that was saved comfortably by Fielding.
After the Cobblers keeper had denied Howard's fierce shot with a superb save, Fryatt incurred the crowd's wrath when, with options to either side, he instead chose a long-range shot which hardly troubled Fielding.