DTC P0037 [LF]: Notes

DTC P0037 (LF) DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0037	HO2S heater circuit low input
DETECTION CONDITION	The PCM monitors the HO2S heater control voltage when the PCM turns the HO2S heater on. If the control voltage is less than 57% of the battery voltage, the PCM determines that the HO2S heater control circuit voltage is low. 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/Mode 12) is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	HO2S connector or terminals malfunction Open circuit or short to ground in HO2S heater power supply circuit Short to ground in wiring harness between ignition relay and HO2S terminal C HO2S heater power supply circuit related fuse malfunction Open circuit in wiring harness between ignition relay and HO2S terminal C HO2S heater malfunction Short to ground in wiring harness between HO2S terminal D and PCM terminal 2BE PCM connector or terminals malfunction Open circuit in wiring harness between HO2S terminal D and PCM terminal 2BE PCM malfunction
Courtesy of MAZDA MOTORS CORP.

DTC P0037

HO2S heater circuit low input

DETECTION CONDITION

The PCM monitors the HO2S heater control voltage when the PCM turns the HO2S heater on. If the control voltage is less than 57% of the battery voltage, the PCM determines that the HO2S heater control circuit voltage is low.

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/Mode 12) is available.
The DTC is stored in the PCM memory.

POSSIBLE CAUSE

HO2S connector or terminals malfunction
Open circuit or short to ground in HO2S heater power supply circuit
- Short to ground in wiring harness between ignition relay and HO2S terminal C
- HO2S heater power supply circuit related fuse malfunction
- Open circuit in wiring harness between ignition relay and HO2S terminal C
HO2S heater malfunction
Short to ground in wiring harness between HO2S terminal D and PCM terminal 2BE
PCM connector or terminals malfunction
Open circuit in wiring harness between HO2S terminal D and PCM terminal 2BE
PCM malfunction

Courtesy of MAZDA MOTORS CORP.