Circuit Description
WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
The DTC P0031 Heated Oxygen Sensor (HO2S) Heater Control Circuit Low Voltage Sensor 1 diagnostic monitors the operation of the HO2S 1 heater circuit. The heaters in the oxygen sensors increase the amount of time the sensor spends in Closed Loop fuel control operation or catalyst monitoring operation. The oxygen sensor heater greatly reduces the amount of time required for the fuel control HO2S 1 to become active. The heater helps provide accurate oxygen content readings of the engine exhaust by the HO2S.