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DTC P0138 [L3]

BME010200100240

DTC P0138 | Rear HO2S circuit high input
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DETECTION CONDITION | • The PCM monitors input voltage from the rear HO2S. If input voltage from the rear HO2S sensor is above 0.45 V for 7 s during deceleration fuel cut, the PCM determines that circuit input is high. Diagnostic support note • This is a continuous monitor (CCM).
• MIL illuminates if 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 PCM detects the above malfunction condition during first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.
POSSIBLE CAUSE | • Rear HO2S malfunction • Short to power circuit in wiring between rear HO2S terminal A and PCM terminal 1Y

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record FREEZE FRAME DATA on repair order, then go to the next step.
2 | VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Check for related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to available Service Information. • If vehicle is not repaired, go to the next step.
No | Go to the next step.
3 | VERIFY RELATED PENDING OR STORED DTCS • Turn the ignition switch off, then to the ON position (Engine off). • Verify pending code or stored DTCs using WDS or equivalent. • Is any other DTC present? | Yes | Go to the applicable DTC inspection. (See DTC TABLE [L3].)
No | Go to the next step.
4 | IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA • Is DTC P0138 on FREEZE FRAME DATA? | Yes | Go to the next step.
No | Go to troubleshooting procedures for DTC on FREEZE FRAME DATA. (See DTC TABLE [L3].)
5 | INSPECT REAR HO2S SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY CIRCUIT • Turn the ignition switch off. • Disconnect the rear HO2S connector. • Turn the ignition switch to the ON position (Engine off). • Measure the voltage between rear HO2S terminal A (wiring harness-side) and body ground.
• Is there any voltage reading?
Yes
Replace short to power supply, then go to Step 7.
No | Go to the next step.
6 | VERIFY CURRENT INPUT SIGNAL STATUS • Start the engine. • Access O2S12 PID using WDS or equivalent. • Verify PID while racing engine at least 10 times (in NEUTRAL). • Does PID reading stay above 0.45 V? | Yes | Repair or replace the sensor, then go to the next step.
No | Go to the next step.
7 | VERIFY TROUBLESHOOTING OF DTC P0138 COMPLETED • Make sure to reconnect all disconnected connectors. • Turn the ignition switch to the ON position (Engine off). • Clear the DTC from the PCM memory using the WDS or equivalent. • Run PCM adaptive memory procedure drive mode and HO2S heater, HO2S, and TWC repair verification drive mode.
(See OBD DRIVE MODE [L3].)
• Is the PENDING CODE of same DTC present.
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [L3].)
No | Go to the next step.
8 | VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [L3].) • Is there any DTC present? | Yes | Go to the applicable DTC inspection. (See DTC TABLE [L3].)
No | Troubleshooting completed.