When Monitored and Set Condition:
WARNING: This page is about a different car, the 2004 Chrysler Pacifica. However, it is still accessible from the selected car via links, so may be relevant.
P0031-O2 SENSOR 1/1 HEATER CIRCUIT LOW
When Monitored: Battery voltage above 10.6 volts, ASD is powered up, and O2 heater is on.
Set Condition: The PCM detects the O2 Heater voltage is out of acceptable range. Below 0.0926 of a volt. One Trip Fault.
P0037-O2 SENSOR 1/2 HEATER CIRCUIT LOW
When Monitored: Battery voltage above 10.6 volts, ASD is powered up, and O2 heater is on.
Set Condition: The PCM detects the O2 Heater voltage is out of acceptable range. Below 0.0926 of a volt. One Trip Fault.