Two tries, one from Akapusi Qera and the other a penalty touchdown, in the last quarter ended a match which failed to inspire.
Home fly-half Freddie Burns booted five penalties in the opening 24 minutes and converted both tries against a solitary penalty from ex-England ace Danny Cipriani for Sale.
But the win was marred by a serious-looking neck injury to the home side's Australia hooker Huia Edmonds 10 minutes into the second half.
Northampton moved into the play-off positions in the Aviva Premiership for at least 24 hours with a hard-fought 23-16 victory over London Welsh amongst the rain and mud at Franklin's Gardens.
After three successive league defeats it was a welcome four points for Northampton, who saw backs coach Paul Grayson leave during the week.
In atrocious conditions it was always going to boil down to a forward battle with Northampton's tries coming through a penalty try and Ken Pisi, though it was London Welsh's pack who made the first impression with a penalty try.