Now they just need a few favours to stay in the hunt for the playoffs.
The win lifted them to 26 points and they sit in seventh place.
But Canterbury, Counties-Manukau and North Harbour can overhaul them with wins in their final round-robin games tomorrow.
Otago lost control of their destiny with a 45-17 lost to Counties-Manukau in Pukekohe last month.
But since that defeat they have registered wins against Manawatū and Tasman to give themselves a chance of slipping into the quarterfinals.
They had to fight back from a 21-10 halftime deficit to defeat Northland.
Otago had all the early possession but were met with some stiff defence from the Taniwha.
Cameron Millar landed a penalty, which was scant reward, all things considered.
Northland had more luck. They scored from their first trip deep inside Otago territory.
Flanker Rob Rush muscled over from the base of a ruck.
The home side added another through lock Allan Craig. He was too big to stop that close to the corner.
Otago needed a spark and the captain provided it.
Christian Lio-Willie took a quick tap and palmed his way past Brady Rush and Terrell Peita before producing a wicked step off his left to defeat the cover defence and score.
But Northland struck back immediately. Rivez Reihana shook off a very limp attempted tackle by Ajay Faleafaga and got the ball to winger Heremaia Murray to finish.
The Taniwha missed an opportunity to further strengthened their grip on the game late in the half.
They battered away but did not crack Otago’s defence and had to settle for an 11-point lead at the break.
Millar nabbed an intercept out wide in the opening exchanges of the second stanza and ran 80m to score what was his first try for Otago. That was just the restart Otago needed.
Their handling kept letting them down, though. They made a series of fumbles in the opening 40 minutes and Harry Taylor dropped the ball with his side in a prime position to strike again.
But the Gore duo combined to put Otago in front.
Millar got a skip pass to Finn Hurley, who had rushed in from fullback on a brilliant angle and burst into a hole.
He finished off with a devastating step off his right foot and ran in under the posts.
Otago’s bench had helped shift the dial and they were finishing strongly.
Front-rowers Liam Coltman and George Bower got the scrum and maul going forward.
Towering lock Fabian Holland scooped up the ball from the back of a ruck and flopped over to score his side’s fourth and secure a bonus point.
Northland replacement front-rower Remsy Lemsio barged over with four minutes remaining to set up a potentially tense finish.
But Otago kept Northland pinned deep in their own territory to close out the game.
The scores
Otago 31 (Christian Lio-Willie, Cameron Millar, Finn Hurley, Fabian Holland tries; Millar 4 con, pen), Northland 28 (Rob Rush, Allan Craig, Heremaia Murray, Remsy Lemsio tries; Rivez Reihana 4 con). Halftime: 21-10 Northland.
