Following just four races of filling in for a recovering Brian Vickers, Mears will see his former Ganassi team-mate Sorenson take over his current drive.
Mears' best finish for the team was a 22nd place on his first weekend driving for Red Bull at Dover, scoring very similar results to his team-mate Scott Speed for the past month.
During last weekend's event at Michigan, Mears was involved in an incident with Speed, then made contact with another driver in the pits and then ended up crashing out of the race.
"Our unique situation has afforded us the opportunity to try some different things, and we're continuing to do that with Reed," said Red Bull Racing Team's Jay Frye. "We appreciate Casey's work and everything he's done the past five weeks."
Sorenson has been running a very limited schedule for Braun Racing in the Sprint Cup this year, although he has not finished in any of his three outings. Driving for the same squad, he had shared duties in the #32 car in the Nationwide Series with Vickers.
This weekendm, two-time DTM champion Mattias Ekstrom will drive the #83 car at Sonoma before Sorenson takes over next week.
Mears will drive for Tommy Baldwin Racing at Loudon, where he will need to make the field on speed.
Moratti calls for Inter focusMears to substitute for unwell Vickers
