Except California Emission Regulation Applicable ATX Model: Notes

DTC P0037 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P0037	Rear HO2S heater circuit low input
DETECTION CONDITION	The PCM monitors the rear HO2S heater output voltage. If the PCM turns the rear HO2S heater off or on but the rear HO2S heater circuit remains low voltage, the PCM determines that the rear HO2S heater circuit has malfunction. 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	Rear HO2S malfunction Open circuit in wiring harness between the ignition switch and rear HO2S terminal C Open circuit in wiring harness between rear HO2S terminal D and PCM terminal 2BE Short to ground in wiring harness between rear HO2S terminal D and PCM terminal 2BE Poor connection at the rear HO2S or the PCM connector PCM malfunction
Courtesy of MAZDA MOTORS CORP.