The Bees started brightly with pacey winger Albert Jarrett’s early cross headed wide by on-loan Exeter man Craig McAllister as Barnet searched for the opener.
The best chance of the first half came after 24 minutes with Jarrett involved again, as his corner was headed goalwards by Ismail Yakubu only for Peter Gilbert to head off the line.
Northampton had to wait until the opening minute of the second half for their first real chance when Luke Guttridge fired wide when clean through on goal.
Things got better for the visitors 15 minutes later, though, when Dean Sinclair was sent off for talking his way into a second booking after fouling Gilbert.
And Northampton thought they had won it late on but Adebayo Akinfenwa’s strike was ruled out for a foul on Barnet goalkeeper Jake Cole.