The 21-year-old is back at Molineux after Wolves keeper Carl Ikeme broke his hand punching a dressing-room tactics board out of frustration at half-time in Saturday's 2-1 win over Bristol City.
McCarey's return is the latest setback in Saddlers manager Dean Smith's troubled and exhaustive search for a regular number one this term.
Hungarian David Grof left the club by mutual consent on Monday and veteran Jimmy Walker recently retired, so the promotion-chasing League One club are set to delve back into the loan market once again.
Walsall started the season with Grof as number one before Karl Darlow was brought in on loan in September and later recalled by parent club Nottingham Forest.
Smith turned to McCarey initially for eight games over November and December before Darlow was re-signed in January and then recalled once more.
Smith subsequently moved for MK Dons keeper Ian McLoughlin in the same month but was unable to extend his stay, meaning a second move for McCarey which has now lasted just one month.