A Fort Worth, Texas, police officer pulled Pachall over at 12:55 a.m. after seeing him run a stop sign and strike a curb. Sgt. Pedro Criado said a breath test revealed Pachall's blood alcohol content was above the 0.08 percent legal limit, but didn't specify what it was, the Fort Worth Star-Telegram reported.
TCU Coach Gary Patterson indefinitely suspended Pachall, who had tested positive for marijuana during the summer.
Pachall has thrown for 948 yards and 10 touchdowns in four games this season. The Horned Frogs, ranked 13th, play Iowa State Saturday.
Pachall will be replaced by redshirt freshman Trevone Boykin in the game, USA TODAY reported.