DTC P0138:00 [PCM (SKYACTIV-X)]

Description	HO2S circuit high input
Detection condition	Determination conditions	• A condition in which the HO2S input voltage exceeds the specified value continues for the specified period.
	Preconditions	• Not applicable
	Malfunction determination period	• 5 s period
	Drive cycle	• 2
	Self test type	• CMDTC self test, KOEO self test, KOER self test
	Sensor used	• HO2S
Fail-safe function	• Inhibits the EGR control.
Vehicle status when DTCs are output	• Not applicable
Possible cause	• HO2S connector or terminals malfunction • PCM connector or terminals malfunction • Short to power supply in HO2S signal circuit • HO2S malfunction • PCM malfunction

• The PCM detects the oxygen concentration in the exhaust gas based on the HO2S signal. The PCM determines a HO2S signal error based on the condition in which the HO2S input voltage continues to exceed the specified value, and stores a DTC.

1. Warm up the engine to allow the engine coolant temperature to reach 80 °C {176 °F} or more.

2. Start the engine and leave it idling for 1 min.

Note

• Match the engine coolant temperature in the recorded freeze frame data/snapshot data, the vehicle speed, and engine speed values to the best extent possible while driving the vehicle.

3. Try to reproduce the malfunction by driving the vehicle for 5 min based on the values in the freeze frame data/snapshot data.

Step	Inspection	Results	Action
1	PURPOSE: VERIFY RELATED REPAIR INFORMATION OR SERVICE INFORMATION AVAILABILITY • Verify related Service Bulletins, on-line repair information, or Service Information availability. • Is any related Information available?	Yes	Perform repair or diagnosis according to the available information. • If the vehicle is not repaired, go to the next step.
1		No	Go to the next step.
2	PURPOSE: RECORD VEHICLE STATUS WHEN DTC WAS DETECTED TO UTILIZE WITH REPEATABILITY VERIFICATION • Record the freeze frame data/snapshot data. Note • Recording can be facilitated using the screen capture function of the PC.	—	Go to Troubleshooting Diagnostic Procedure to perform the procedure from Step 1.

• Repair completion verification

Step	Inspection	Results	Action
1	PURPOSE: INSPECT HO2S CONNECTOR FOR MALFUNCTION • Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION.) • Are the connector and terminal normal?	Yes	Go to the next step.
1		No	Repair or replace the malfunctioning location and perform the repair completion verification.
2	PURPOSE: INSPECT PCM CONNECTOR FOR MALFUNCTION • Inspect the applicable connector and terminal. (See CONNECTOR INSPECTION.) • Are the connector and terminal normal?	Yes	Go to the next step.
2		No	Repair or replace the malfunctioning location and perform the repair completion verification.
3	PURPOSE: INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY • Inspect the applicable circuit for a short to power supply. (See CIRCUIT INSPECTION.) • Is the circuit normal?	Yes	Go to the next step.
3		No	Repair or replace the malfunctioning location and perform the repair completion verification.
4	PURPOSE: INSPECT HO2S FOR MALFUNCTION • Inspect the applicable part. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-X 2.0].) • Is the part normal?	Yes	Go to the next step.
4		No	Repair or replace the malfunctioning location and perform the repair completion verification. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
Repair completion verification 1	PURPOSE: VERIFY THAT VEHICLE IS REPAIRED • Install/connect the part removed/disconnected during the troubleshooting procedure. • Clear the DTC recorded in the memory. (See CLEARING DTC.) • Replicate the vehicle conditions at the time the DTC was detected using the following procedure. ― Perform the KOEO or KOER self test. (See DTC INSPECTION.) • Perform the DTC inspection for the PCM. (See DTC INSPECTION.) • Is the same Pending DTC present?	Yes	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW [(E)].) If the CAN communication is normal, perform the diagnosis from Step 1. • If the malfunction recurs, replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
Repair completion verification 1		No	Go to the next step.
Repair completion verification 2	PURPOSE: VERIFY IF OTHER DTCs DISPLAYED • Perform the DTC inspection. (See DTC INSPECTION.) • Are any other DTCs displayed?	Yes	Repair the malfunctioning location according to the applicable DTC troubleshooting.
Repair completion verification 2		No	DTC troubleshooting completed.

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