General Information

Component Location





General Description

The normal operating temperature of the HO2S (Heated Oxygen Sensor) ranges from 350 to 850 °C (662 to 1562 °F). The HO2S heater greatly decreases the amount of time required for fuel control to become active. The ECM provides a pulse width modulated control circuit to adjust current through the heater. When the HO2S is cold, the value of the resistance is low and the current in the circuit is high. On the contrary, if the temperature in the resistor of the sensor rises, the current drops gradually.

DTC Description

ECM sets DTC P0031 if the ECM detects that the front HO2S heater control circuit is short to ground.

DTC Detecting Condition





Specification





Schematic Diagram





Signal Waveform




The HO2S requites a minimum temperature to provide a closed loop fuel control system. So the HO2S contains a heater element to reduce its warm-up time and ensure its performance during all driving conditions. The HO2S heater should always be ON after engine start. The ECM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the ECM provides a ground circuit for activating the heater. The illustration is the signal waveform at idle after the HO2S heater completes warm-up.