DTC P0137: Notes

DETECTION CONDITION AND POSSIBLE CAUSE (DTC P0137)

DTC P0137	Rear HO2S circuit low input
DETECTION CONDITION	The PCM monitors input voltage from rear HO2S. If the input voltage from the rear HO2S is below 0.1 V for 35.2 s the PCM determines that circuit input is low. MONITORING CONDITIONS HO2S, HO2S heater and TWC repair verification drive mode Following conditions are met. Engine speed is above 1,500 rpm . Engine coolant temperature is above 70°C {158°F} . Fuel injector control in rear HO2S closed loop control. The PCM monitors the input voltage from the rear HO2S when the following conditions are met. Under the following monitoring conditions, if the input voltage from the rear HO2S does not even exceed 0.1 V though the short term fuel trim is controlled up to 20.5% for 9.6 s , the PCM determines that sensor circuit input is low. MONITORING CONDITIONS HO2S, HO2S heater and TWC repair verification drive mode Following conditions are met for above 20.8 s . Engine speed is above 1,500 rpm . Engine coolant temperature is above 70°C {158°F} . Diagnostic support note This is a continuous monitor (HO2S). The MIL illuminates if the PCM detects 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	Rear HO2S malfunction Short to body ground circuit in wiring between rear HO2S terminal A and PCM terminal 2Q Open circuit in wiring between rear HO2S terminal A and PCM terminal 2Q Open circuit in wiring between rear HO2S terminal B and PCM terminal 2BH PCM malfunction
Courtesy of MAZDA MOTORS CORP.

DTC P0137

Rear HO2S circuit low input

DETECTION CONDITION

The PCM monitors input voltage from rear HO2S. If the input voltage from the rear HO2S is below 0.1 V for 35.2 s the PCM determines that circuit input is low.
MONITORING CONDITIONS
- HO2S, HO2S heater and TWC repair verification drive mode
- Following conditions are met.
  - Engine speed is above 1,500 rpm .
  - Engine coolant temperature is above 70°C {158°F} .
  - Fuel injector control in rear HO2S closed loop control.
The PCM monitors the input voltage from the rear HO2S when the following conditions are met. Under the following monitoring conditions, if the input voltage from the rear HO2S does not even exceed 0.1 V though the short term fuel trim is controlled up to 20.5% for 9.6 s , the PCM determines that sensor circuit input is low.
MONITORING CONDITIONS
- HO2S, HO2S heater and TWC repair verification drive mode
- Following conditions are met for above 20.8 s .
  - Engine speed is above 1,500 rpm .
  - Engine coolant temperature is above 70°C {158°F} .

Diagnostic support note

This is a continuous monitor (HO2S).
The MIL illuminates if the PCM detects 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

Rear HO2S malfunction
Short to body ground circuit in wiring between rear HO2S terminal A and PCM terminal 2Q
Open circuit in wiring between rear HO2S terminal A and PCM terminal 2Q
Open circuit in wiring between rear HO2S terminal B and PCM terminal 2BH
PCM malfunction

Courtesy of MAZDA MOTORS CORP.