DTC P1031: Ho2S Bank 1 & 2 Sensor 1 Heater Current Monitor Control Circuit: Description
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
The Heated Oxygen Sensor (HO2S) heater is used to reduce the time that the sensor takes to become go active. The Powertrain Control Module (PCM) controls the HO2S heaters using the low side ODM drivers. The PCM uses a current monitoring driver in order to test the condition of the fuel control heaters. A high side driver provides the HO2S bank 1 sensor 1 heater with ignition voltage. A low side driver provides the ground path for both of the heaters. With the engine running, the PCM turns ON the high side driver and the low side driver in order to warm the oxygen sensors. If the PCM detects an incorrect circuit condition for the commanded state of the current monitoring driver, this DTC will set.