The Camry and Camry hybrid, Avalon and Avalon hybrid and Venza from the 2012 and 2013 model years are affected.
Toyota says water from the air conditioning condenser can leak onto the air bag control module and cause a short circuit. That could illuminate the air bag warning light, disable the air bag or cause the air bags to deploy inadvertently.
The power steering assist function could also become inoperable if the air bag control module is damaged, making the vehicles harder to steer.
Toyota knows of two minor injuries, but no accidents, related to the defect.
Owners will be notified starting next month. Toyota dealers will repair the problem for free.