Circuit Description

The heated oxygen sensor (HO2S) must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. With the engine running, ground is provided to the heater by the HO2S heater low control circuit, through a low side driver within the engine control module (ECM). The ECM commands the heater ON or OFF to maintain a specific HO2S operating temperature range. The ECM monitors the current flow through the heater for diagnosis. If the ECM detects that the current is above or below a specified range, DTCs P0141 sets.