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DTC P0137

DTC P0137 HO2S circuit low input
DETECTION CONDITION 
  • The PCM monitors input voltage from the HO2S. If the input voltage from the HO2S is below -0.95 V for 5 s  while the HO2S is active or HO2S bias voltage below 1.3 V for 5 s,  the PCM determines that circuit input is low.

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 (Mode 2/Mode 12) is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • HO2S connector or terminals malfunction
  • Short to ground in wiring harness between HO2S terminal A and PCM terminal 20.
  • Short to ground in wiring harness between HO2S terminal B and PCM terminal 2BH
  • PCM connector or terminals malfunction
  • Open circuit in wiring harness between HO2S terminal A and PCM terminal 2Q
  • Open circuit in wiring harness between HO2S terminal B and PCM terminal 2BH
  • HO2S malfunction
  • PCM malfunction
G07878110
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2) 
  • Is the DTC P0137 on FREEZE FRAME DATA (Mode 2)?
 Yes Go to the next step.
No Go to the troubleshooting procedure for DTC on FREEZE FRAME DATA (Mode 2).
(See DTC TABLE ).
2 VERIFY FREEZE FRAME DATA (MODE 12) AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor, HO2S related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
3 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.
4 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 ).
No Go to the next step.
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 pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector and/or terminals, then go to Step 10.
No Go to the next step.
6 INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO GROUND 
  • HO2S connector is disconnected.
  • Turn the ignition switch off.
  • Inspect for continuity between the following circuits:
    • HO2S terminal A (wiring harness-side) and body ground
    • HO2S terminal B (wiring harness-side) and body ground
  • Is there continuity?
 Yes If the short to ground circuit could be detected:
  • Repair or replace the wiring harness for a possible short to ground.

If the short to ground circuit could not be detected:
Go to Step 10.
No Go to the next step.
7 INSPECT PCM CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector and/or terminals, then go to Step 10.
No Go to the next step.
8 INSPECT HO2S CIRCUIT FOR OPEN CIRCUIT 
  • HO2S and PCM connectors are disconnected.
  • Turn the ignition switch off.
  • Inspect for continuity between the following circuits:
    • 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 Step 10.
9 INSPECT HO2S 
 Yes Replace the HO2S, then go to the next step.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
No 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 the M-MDS.

    (See AFTER REPAIR PROCEDURE ).

  • Perform the DRIVE MODE 3 (A/F sensor heater, HO2S heater, A/F sensor, HO2S, and TWC Repair Verification Drive Mode).

    (See OBD-II DRIVE MODE ).

  • Is the PENDING CODE for this DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION ).
No Go to the next step.
11 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No DTC troubleshooting completed.
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