The Chiefs came into the game against Bath, who they have still never beaten, knowing that a win would be needed to keep pace with Harlequins in Pool 1, while Bath trailed Saints by a point.
But after a first-half in which the teams could not be split, it was Stringer's introduction which turned it around.
Stringer wasn't the only player making his first Bath appearance, with Rob Webber getting a valuable 40 minutes after an injury-hit season, while Matt Gilbert started in the back row.
Bath made the quicker start with an early penalty from fly-half Tom Heathcote getting them on the board after just four minutes.
But Exeter hit back through their own young fly-half Henry Slade, after the home side had been penalised for slowing the ball down.
The Chiefs were beginning to find their feet but contrived to throw away a glorious opportunity soon after.
A barrage of attacks from the visitors had left the Bath defensive line in tatters, and when the ball was spread wide there was a three-man overlap.
Instead of the certain try, the ball went forward to second row Will Carrick-Smith and his effort was ruled out.
Still, the Chiefs were in the ascendancy and added a second penalty after 23 minutes, from Slade, to take the lead for the first time.
After a sickening clash which saw Ben Williams go off with injury, Heathcote levelled things to make it 6-6 at the break.
Just before half-time Bath also brought on debutant Stringer, who replaced Mark McMillan, and he made an immediate impact.
Just ten minutes into the second half, the Irishman darted over after a lineout drive from the home side.
Leading 11-6, Bath made the bold call to turn down a kickable penalty and instead kicked for the corner.
And the gamble paid off as the veteran scrum-half showed his quick-thinking and quick feet to nip over and make it 16-6.
The Chiefs kept attacking, and looked certain to score on a number of occasions but poor finishing let them down as they left the Rec empty-handed, knowing that next week's clash with Saints is now a must-win affair.
Bath meanwhile are still very much alive ahead of their trip to local rivals Gloucester next Saturday.