DTC P0138 [L3 Turbo]

id0102b7805100

DTC P0138

HO2S circuit high input

DETECTION CONDITION

•  The PCM monitors the input voltage from the HO2S. If the input voltage from the HO2S sensor is above 1.2 V for 0.8 s, the PCM determines that the circuit input is high.

Diagnostic support note

•  This is an intermittent monitor (A/F sensor, HO2S).

•  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 first drive cycle.

•  FREEZE FRAME DATA is available.

•  DTCs are stored in the PCM memory.

POSSIBLE CAUSE

•  Short to power supply in the wiring harness between HO2S terminal A and PCM terminal 2Q

•  HO2S or PCM terminal shorted

•  HO2S malfunction

•  PCM malfunction

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

Diagnostic procedure

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED • Have the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor, HO2S related) been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2	VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Verify related Service Information availability. • Is any related Service Information available?	Yes	Perform the repair or diagnosis according to available Service Information. • If vehicle is not repaired, go to the next step.
2		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 M-MDS. • Is other DTC present?	Yes	Go to the appropriate DTC troubleshooting procedures. (SeeDTC TABLE [L3 Turbo].)
3		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.
4		No	Go to the troubleshooting procedures for the DTC on the FREEZE FRAME DATA. (SeeDTC TABLE [L3 Turbo].)
5	INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY • Turn the ignition switch off. • Disconnect HO2S and PCM connectors. • Turn the ignition switch to the ON position. (Engine off) • Measure the voltage between HO2S terminal A (wiring harness-side) and body ground. • Is there any voltage?	Yes	Replace short to power supply, then go to Step 8.
5		No	Go to the next step.
6	INSPECT HO2S CIRCUIT FOR SHORT TO WIRING HARNESSES • HO2S and PCM connectors disconnected. • Inspect for continuity between HO2S sensor terminal Aand B (wiring harness-side). • Is there continuity?	Yes	Replace the sensor, then go to the next step. (SeeEXHAUST SYSTEM REMOVAL/INSTALLATION [L3 Turbo].)
6		No	Go to the next step.
7	INSPECT HO2S • Inspect the HO2S. (See AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) INSPECTION [L3 Turbo].) • Is HO2S normal?	Yes	Go to the next step.
7		No	Replace the sensor, then go to the next step. (See EXHAUST SYSTEM REMOVAL/INSTALLATION [L3 Turbo].)
8	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 M-MDS. • Run the PCM adaptive memory procedure drive mode and A/F sensor heater, HO2S heater, A/F sensor, HO2S, and TWC repair verification drive mode. (SeeOBD DRIVE MODE [L3 Turbo].) • Is the PENDING CODE for this DTC present?	Yes	Replace the PCM, then go to the next step. (SeePCM REMOVAL/INSTALLATION [L3 Turbo].)
8		No	Go to the next step.
9	VERIFY AFTER REPAIR PROCEDURE • Perform the “AFTER REPAIR PROCEDURE”. (SeeAFTER REPAIR PROCEDURE [L3 Turbo].) • Are any DTCs present?	Yes	Go to the applicable DTC troubleshooting. (SeeDTC TABLE [L3 Turbo].)
9		No	Troubleshooting completed.