Note. For circuit reference, see DTC P0131 schematic.
Circuit Description
PCM provides about 0.45 volt reference to HO2S 1. HO2S 1 sensor signal voltage varies from about one volt when exhaust is rich to about 0.1 volt when exhaust is lean. PCM reads and stores sensor voltage information and evaluates the voltage samples to determine amount of time sensor voltage is out of range. If HO2S 1 voltage is out of predetermined range, DTC will set.