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DTC P0138 [L8, LF, L3]

id0102a1805100

DTC P0138 | HO2S circuit high input
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DETECTION CONDITION | • The PCM monitors input voltage from HO2S. If the input voltage from the HO2S is above 1.2 V for 0.8 s, the PCM determines that circuit input is high. Diagnostic support note • This is a continuous monitor (A/F sensor , HO2S). • 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 first drive cycle. • FREEZE FRAME DATA is available. • DTC is stored in the PCM memory.
POSSIBLE CAUSE | • HO2S malfunction • Short to power supply in wiring harness between HO2S terminal A and PCM terminal 2Q • HO2S or PCM terminal shorted • PCM malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record the FREEZE FRAME on the repair order, then go to the next step.
2 | VERIFY RELATED REPAIR INFORMATION AVAILABILITY • Verify related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to the available Service information. If the vehicle is not repaired, go to the next step.
No | Go to the next step.
3 | VERIFY RELATED PENDING OR STORED DTC • Turn the ignition switch off, then to the ON position. (Engine off) • Verify pending code or stored DTCs using the WDS or equivalent. • Are other DTCs present? | Yes | Go to the appropriate DTC troubleshooting procedures. (See DTC TABLE [L8, LF, L3].)
No | Go to the next step.
4 | IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA • Is the 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 [L8, LF, L3].)
5 | INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY • Turn the ignition switch off. • Disconnect HO2S connector. • Turn the ignition switch to the ON position. (Engine off) • Measure the voltage between HO2S terminal A (wiring harness-side) and body ground. • Is the voltage B+? | Yes | Replace a 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 the WDS or equivalent. • Verify PID while racing engine at least 10 times in PARK (ATX) or NEUTRAL (MTX). • Does PID stay above 0.55 V? | Yes | Replace the sensor, then go to the next step. (See EXHAUST SYSTEM REMOVAL/INSTALLATION [L8, LF, L3 2WD].) (See EXHAUST SYSTEM REMOVAL/INSTALLATION [L3 4WD].)
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 memory using the WDS or equivalent. • Perform the KOEO or KOER self-test. (See KOEO/KOER SELF TEST [L8, LF, L3].) • Is the DTC P0138 present? | Yes | Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L8, LF, L3].)
No | Go to the next step.
8 | VERIFY AFTER REPAIR PROCEDURE • Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE [L8, LF, L3].) • Are any DTC present? | Yes | Go to the applicable DTC troubleshooting. (See DTC TABLE [L8, LF, L3].)
No | Troubleshooting completed.