The summer signing struck from a free-kick in the 90th minute to cancel out Anthony Straker's goal for the hosts, a third time in as many games that York have conceded in the dying stages.
"We need to improve our concentration," said manager Nigel Worthington afterwards.
Chris Wilder will be delighted to see his side remain unbeaten after the opening week of the season and not suffer an immediate comedown from the League Cup victory at Wolves.
"That's why we brought Marc to the club to produce moments like that," said the Cobblers boss.