DTC P0031:00: Notes

DTC P0031:00	A/F sensor heater control circuit low input
DETECTION CONDITION	The PCM monitors the A/F sensor heater output voltage. If the PCM turns the A/F sensor heater off but the A/F sensor heater circuit remains low voltage, the PCM determines that the A/F sensor heater circuit has a malfunction. Diagnostic support note This is a continuous monitor (A/F sensor heater, HO2S heater). The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2)/Snapshot data is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	A/F sensor connector or terminal malfunction Short to ground or open circuit in A/F sensor heater power supply circuit Short to ground in wiring harness between main relay terminal D and A/F sensor terminal A ENGINE 10 A fuse malfunction Open circuit in wiring harness between main relay terminal D and A/F sensor terminal A Short to ground in wiring harness between A/F sensor terminal E and PCM terminal 2A A/F sensor heater malfunction PCM connector or terminal malfunction Open circuit in wiring harness between A/F sensor terminal E and PCM terminal 2A PCM malfunction