Akinfenwa struck with virtually the last kick of the match in the third minute of stoppage time as the Cobblers appeared to be heading for defeat, trailing as they were to a goal from Phil Jevons and reduced to ten men after the sending-off of Jason Crowe for a trip on Gary Roberts 16 minutes from time.
It was a blow for Huddersfield whose new manager Lee Clark has now been installed for a month and although the Yorkshire side beat the freeze for a second week running, they will be disappointed to record a second straight 1-1 draw with their sights set on the play-offs.
Huddersfield made most of the running in the first half, but they have should have gone behind in the 12th minute when Akinfenwa played in Crowe but with just Alex Smithies to beat, the utility man side-footed his shot wide.
Danny Cadamarteri was a constant thorn in the home defence and his 16th minute snap-shot was parried away by Chris Dunn, while the visitors almost went ahead in the 24th minute when Jevons turned sweetly on the edge of the box but saw his shot whistle past Dunn's right-hand post.
Northampton went close after the restart when Abdul Osman fired a 25-yarder over the bar, but the visitors went in front from a free-kick in the 65th minute.
Osman was penalised for a foul and Jevons stepped up to snake a free-kick around the wall and inside Dunn's right-hand post.
Northampton had only scored once in their previous three games and things looked bleak when Crowe was dismissed.
But they came up trumps in stoppage time when a cross from the left was only half cleared into Akinfenwa's path and the striker gleefully drilled home his ninth goal of the season from 15 yards.