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DTC P0038

DTC P0038 HO2S heater control circuit high input
DETECTION CONDITION 
  • The input voltage to the HO2S heater drive terminal in the PCM is at the set value or more for 0.5 s or more  even though the HO2S heater is duty-controlled at 10 % or more  by the PCM.
  • If the current flowing to the HO2S heater circuit in the PCM is high when the HO2S heater is off, the PCM detects DTC P0038.

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
  • HO2S heater malfunction
  • PCM connector or terminals malfunction
  • Short to power supply in wiring harness between HO2S terminal D and PCM terminal 2BE
  • PCM malfunction
G07878095
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 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 heater, HO2S heater 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.
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 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, and corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector and/or terminals, then go to Step 7.
No Go to the next step.
4 INSPECT HO2S HEATER 
 Yes Replace the HO2S, then go to Step 7.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION ).
No Go to the next step.
5 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, and corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector and/or terminals, then go to Step 7.
No Go to the next step.
6 INSPECT HO2S HEATER CONTROL CIRCUIT FOR SHORT TO POWER SUPPLY 
  • HO2S and PCM connectors are disconnected.
  • Turn the ignition switch to the ON position (engine off).
  • Measure the voltage between HO2S terminal D (wiring harness-side) and body ground.
  • Is the voltage B+? 
 Yes Repair or replace the wiring harness for a possible short to power supply, then go to the next step.
No Go to the next step.
7 VERIFY TROUBLESHOOTING OF DTC P0038 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 KOEO or KOER self test.

    (See KOEO/KOER SELF TEST ).

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