The Sheffield United loanee gave Latics the lead on 35 minutes through a powerful header but Ikpeazu’s strike 20 minutes from time meant David Dunn had to settle for a third consecutive draw as manager.
Dunn made one change to the starting 11 which drew 1-1 with Wigan Athletic on Saturday as goalscorer Dominic Poleon replaced Danny Philliskirk.
It was a lively start to the game as Latics won the first corner of the game 15 seconds in. Port Vale broke but Connor Brown was back to win a free kick as the home side attacked.
Poleon started the half on the left hand side and broke with two minutes on the clock. He cut inside and shot but it was just cleared at the last.
Port Vale looked threatening in attack and former Crewe Alexandra man Ajay Leitch Smith whipped in a dangerous cross on seven minutes but David Cornell held onto the ball well as strikers looked to pounce.
Latics were unlucky not to take the lead on 13 minutes as Mike Jones opened fire from the edge of the box but Jak Alnwick parried around the post.
That effort seemed to kick the home side into action and they had a 10 minute spell of dominance but struggled to create a clear cut goalscoring opportunity.
Winger Enoch Andoh’s pace was causing Tim Dieng a problem on the left side and his trickery earned Vale a free kick midway through the first half.
From that free kick, Dickinson’s cross into the box was headed goalwards by defender Remie Streete but Jones was back on the line to head over the crossbar.
With the Valiants knocking on the door for the opening goal, Dunn switched systems and changed to a 4-4-2 with Poleon partnering Higdon into attack.
That move would later come to work in the interim manager’s favour but on the half hour mark, Latics had to be alert as Leitch Smith was in space in the box but Jonathan Burn was back to make the crucial tackle.
Five minutes later, however, Latics were in front through the head of Sheffield United loanee Higdon.
It initially started with great pressure from Poleon, who did not give up the ball in the Port Vale back line and won a corner out of nothing for Latics.
Jones’ resulting set piece found the head of Higdon, who had peeled away from his defender, and his powerful header found a way past the Alnwick and Latics were a goal to the good.
Just before the half time break, Higdon could have doubled Athletic’s lead. Poleon’s initial shot was destined for the bottom corner before Alnwick palmed the ball out as far as Higdon but the striker blasted over from close range.
Latics started the second half much the same as they ended the first, on the front foot.
Poleon was at the forefront of the attack for Latics and five minutes into the second half, he received the ball inside the penalty area but Streete was back to defend for the home side.
Five minutes later, Latics could and maybe should have extended their lead through the former Leeds United man.
The striker received the ball in acres of space in the penalty area after Dieng intercepted but he snatched at the shot and dragged it wide of Alnwick’s goal.
Both sides made a change on the hour mark as Vale brought on Uche Ikpeazu and he proved to be a handful for the defence which his pace and power.
Five minutes after his introduction, he knocked the ball back for Anthony Grant to strike but Latics defended in numbers and blocked the shot.
It was proving to be backs against the walls stuff for Athletic as they looked to hold on to their lead.
However, with 20 minutes of the game remaining, the Valiants found themselves level through the substitute striker Ikpeazu.
Burn found himself out of position and with three against two at the back, Moore crossed to the striker and he prodded past Cornell to equalise.
The goal seemed to kick Latics back into life in the second half and the game started to become more open.
Poleon continued to cause a nuisance in attack and with 75 minutes on the clock, he chased down a loose ball back to the goalkeeper but he just got to it before the goalkeeper.
Substitutes Danny Philliskirk and Mark Yeates both had efforts going into the final 10 minutes of the game but both failed to test the goalkeeper.
Five minutes before the end of normal time, Philliskirk struck from the edge of the box which provoked a smart save from Alnwick, whilst at the other end the defence had to be resolute to deny Port Vale a late winner.
They almost got that in the final minute of the game but Cornell held onto a cross into the box which bounced around for what seemed an age.
The referee blew the final whistle seconds later and Dunn had to settle for another point in his third game in charge of Latics.
Port Vale: Alnwick, Purkiss, Streete, Duffy, Dickinson, Moore, Grant, Foley, Andoh, Leitch-Smith (Ikpeazu 57’), Daniel.
Subs not used: Johnson, McGivern, Birchall, Brown, Hooper, Lloyd.
Oldham Athletic: Cornell, Dieng, J.Wilson, Burn, Brown, Kelly, Jones, Croft (Yeates 60’), Fulton (Philliskirk 70’), Poleon, Higdon (Stankevicius 86’).
Subs not used: Coleman, Eckersley, Edmundson, Winchester.
Goals: Port Vale (Ikpeazu 70’) 1-1 Oldham Athletic (Higdon 35’)
Attendance: 4,065 (281 visiting supporters)