Circuit Description

HO2S2 is located behind catalytic converter. Sensor is used by PCM to determine oxygen storage capability of catalytic converter. Heater in sensor speeds up sensor activation time. PCM commands heater on after the first 45 seconds of engine run time and turns off when engine is turned off. DTC will set when heater current draw is too low (less than 0.5 amp) when heater is commanded on.