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DTC P0137 [13B-MSP]

DTC REFERENCE CHART

DTC P0137 HO2S circuit low input
DETECTION CONDITION 
  • The PCM monitors input voltage from HO2S. If the input voltage from the HO2S is below 0.1 V for 35.2 s  the PCM determines that circuit input is low.

    MONITORING CONDITIONS 

    • A/F sensor heater, HO2S heater, A/F sensor, HO2S, 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 HO2S closed loop control.
  • The PCM monitors the input voltage from the HO2S when the following conditions are met. Under the following monitoring conditions, if the input voltage from the HO2S does not even exceed 0.1 V  though the short term fuel trim is controlled, the PCM determines that sensor circuit input is low.

    MONITORING CONDITIONS 

    • A/F sensor heater, HO2S heater, A/F sensor, HO2S, 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 (A/F sensor, HO2S.)
    • The MIL illuminates if PCM detects the above malfunctioning 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 PCM detects the above malfunction conditions during the first drive cycle.
    • FREEZE FRAME DATA is available.
    • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Connector or terminal malfunction
  • Short to ground in wiring between HO2S terminal A and PCM terminal 2Q
  • HO2S malfunction
  • Open circuit in wiring between HO2S terminal A and PCM terminal 2Q
  • Open circuit in wiring between HO2S terminal B and PCM terminal 2BH
  • PCM malfunction
G05982322Courtesy of MAZDA MOTORS CORP.
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor, HO2S related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
 Yes Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 VERIFY RELATED PENDING CODE OR STORED DTC 
  • Turn the ignition switch off, then ON position (engine off.)
  • Verify the related PENDING CODE or stored DTCs using M-MDS.
  • Is other DTC present?
 Yes Go to appropriate DTC troubleshooting procedure. (See DTC TABLE [13B-MSP] .)
No Go to the next step.
4 IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA 
  • Is DTC P0137 on FREEZE FRAME DATA?
 Yes Go to the next step.
No Go to troubleshooting for DTC on FREEZE FRAME DATA. (See DTC TABLE [13B-MSP] .)
5 INSPECT HO2S CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect the HO2S connector.
  • Inspect for poor connection (such as damaged, pulled-out terminals, corrosion.)
  • Is there any malfunction?
 Yes Repair or replace the terminal, then go to Step 10.
No Go to the next step.
6 INSPECT PCM CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged, pulled-out terminals, corrosion.)
  • Is there any malfunction?
 Yes Repair or replace the terminal, then go to Step 10.
No Go to the next step.
7 INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO GROUND 
  • Turn the ignition switch off.
  • Inspect for continuity between HO2S terminal A (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Repair or replace the wiring harness for a possible short to ground, then go to Step 10.
No Go to the next step.
8 INSPECT HO2S  Yes Replace the HO2S, then go to Step 10. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [13B-MSP] .)
No Go to the next step.
9 INSPECT HO2S GROUND CIRCUIT FOR OPEN CIRCUIT 
  • Turn the ignition switch off.
  • Inspect for continuity between the following circuit:
    • HO2S terminal A (wiring harness-side) and PCM terminal 2Q (wiring harness-side)
    • HO2S terminal B (wiring harness-side) and PCM terminal 2BH (wiring harness-side)
  • Is there continuity?
 Yes Go to the next step.
No Repair or replace the wiring harness for a possible open circuit, then go to the next step.
10 VERIFY TROUBLESHOOTING OF DTC P0137 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using M-MDS.
  • Perform the DRIVE MODE 3. (See OBD-II DRIVE MODE [13B-MSP] .)
  • Is the PENDING CODE for this DTC present?
 Yes Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [13B-MSP] .)
No Go to the next step.
11 VERIFY AFTER REPAIR PROCEDURE  Yes Go to applicable DTC inspection. (See DTC TABLE [13B-MSP] .)
No DTC troubleshooting completed.
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