Home › Chrysler › 2003 › Voyager Base, 2.4 B › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes - 2.4L › Diagnostic Tests › DTC P0031: O2 Sensor 1/1 Heater Circuit Low Or P0037: O2 Sensor 1/2 Heater Circuit Low › Possible Causes