Sawyer levelled from John-Paul Pittman's cross to cancel out Lee Collins' 61st minute opener.
Despite a 1-0 win at Luton in midweek, Wycombe boss Peter Taylor rung the changes with Chris Zebroski, Tom Doherty, Matt Bloomfield and Sawyer coming back into his side.
And in a scrappy opening, Bloomfield almost gave the visitors a ninth minute lead when he latched onto John Akinde's flick-on to hit a shot which was well saved by Chris Martin.
Martin was again on hand to deny a Zebroski effort in the 16th minute as the Chairboys took control of the game.
And in the 30th minute Sawyer found Akinde in space, before the in-form striker placed his shot into the arms of the Vale keeper.
On-loan Chelsea midfielder Sawyer was beginning to pull the strings as Wycombe looked to unlock a stubborn defence.
Wycombe began to look more dangerous after the break and almost went ahead when David McCracken's 55th minute header was cleared off the line by Paul Edwards.
But Vale took the lead against the run of play in the 61st minute. Paul Marshall's inswinging corner fell nicely for Collins to fire his third of the season from five yards out.
Danny Glover should have doubled their advantage five minutes later, but was denied from close range after Jamie Young had spilled Marshall's original shot.
Pittman bounced off the bench in the 78th minute and conjured the equaliser less than two minutes later. His surging run and low cross presented a simple tap-in for Sawyer from six yards.
Wycombe now need a point at home to Notts County next weekend to ensure promotion.