Conditions for Clearing the MIL/DTC

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

DTC P0138

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Start the engine. Allow the engine to idle at operating temperature. Refer to Scan Tool Data List . Quickly cycle the throttle from closed throttle to wide open throttle 3 times while observing the HO2S 2 parameter with a scan tool. Does the voltage vary above and below the specified range?	390-520 mV	Go to Step 3	Go to Step 4
3	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 4	Go to Intermittent Conditions
4	Turn OFF the ignition. Disconnect the heated oxygen sensor (HO2S) 2. Turn ON the ignition, with the engine OFF. Observe the HO2S 2 parameter with a scan tool. Is the voltage more than the specified value?	500 mV	Go to Step 5	Go to Step 6
5	Test the HO2S 2 high signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 8
6	Inspect for the following conditions that may affect the HO2S operation: NOTE: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in Cautions and Notices. HO2S contamination - Inspect the HO2S for contamination. NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Chafed, burnt, cut, pinched, or otherwise damaged HO2S wiring Exhaust system leaks or restrictions Evaporative emissions (EVAP) system malfunction - Inspect the EVAP control system. Refer to Inspection/Maintenance (I/M) Evaporative Emission (EVAP) System Set Procedure . Incorrect fuel pressure - Refer to Fuel System Diagnosis . Did you find and correct the condition?	-	Go to Step 11	Go to Step 7
7	Test for shorted terminals and poor connections at the HO2S 2. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 9
8	Test for shorted terminals and poor connections at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 10
9	NOTE: Refer to Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice in Cautions and Notices. Replace the HO2S 2. Refer to Heated Oxygen Sensor Replacement - Position 2 .Did you complete the replacement?	-	Go to Step 11	-
10	Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming. Did you complete the replacement?	-	Go to Step 11	-
11	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 12
12	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK