Sheehan scored six minutes from the end with a superb top-corner volley from a Luton corner to earn his side a share of the spoils following Liam Walsh's opener for Yeovil fourteen minutes earlier.
The Irish defender has featured in all three of Luton's games so far since his arrival at Kenilworth Road in January on loan until the end of the season.
Another City player currently on loan away from the Coral Windows Stadium is Dylan Mottley-Henry.
The young winger signed a loan deal with National Conference side Altrincham the middle of last month, featuring in both of their first team games since then.
Mottley-Henry started his debut game at Grimsby Town before coming on as a late substitute in Altrincham's home win over Woking three days later.