O2 SENSOR

A pending code means that the fault with the B1S2 oxygen sensor has occurred once and if it occurs again ( most likely it will ) then the code will be considered a 'hard fault' and will illuminate the Check Engine Light and will record the vehicle running conditions present while the fault occurred in what is called a 'freeze frame'. A modern vehicle like your Toyota truck, has a very sophisticated computer system with multiple software programs that run constantly to monitor and adapt the vehicle running conditions, every minute your are driving, in order to compensate for wear from the mileage being put on the vehicle.