DTC P0031: Notes

DTC P0031 [L3] CHART

DTC P0031	Front HO2S heater circuit low input
DETECTION CONDITION	The PCM monitors the front HO2S heater output voltage. If the PCM turns the front HO2S heater off or on but the front HO2S heater circuit remains low voltage, the PCM determines that the front HO2S heater circuit has malfunction. NOTE: The front HO2S heater is controlled by duty signal. Diagnostic support note This is a continuous monitor (HO2S heater). 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 is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	Front HO2S malfunction Open circuit in wiring harness between IG1 and front HO2S terminal C Open circuit in wiring harness between front HO2S terminal D and PCM terminal 2G Short to ground in wiring harness between front HO2S terminal D and PCM terminal 2G Poor connection at front HO2S or the PCM connector PCM malfunction