California Emission Regulation Applicable ATX Model: Notes

DTC P0037 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P0037	Middle HO2S heater circuit low input
DETECTION CONDITION	The PCM monitors the middle HO2S heater control voltage when the PCM turns the middle HO2S heater off. If the control voltage exceeds 25%  of the battery voltage, the PCM determines that the middle HO2S heater control circuit voltage is low. Diagnostic support note  This is a continuous monitor (HO2S heater). MIL illuminates if PCM detects above malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM. PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle. FREEZE FRAME DATA is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	Middle HO2S heater malfunction Connector or terminal malfunction Short to power supply in wiring harness between middle HO2S terminal D and PCM terminal 2BF PCM malfunction
Courtesy of MAZDA MOTORS CORP.