Circuit Description

PCM supplies about 450 millivolts (mV) between HO2S high and low signal circuits. The HO2S voltage ranges from about 1000 mV when exhaust is rich to about 10 mV when exhaust is lean. PCM monitors and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If PCM detects HO2S voltage is out the bias range, DTC will set.