Conditions for Clearing the MIL/DTC

WARNING: This page is about a different variant/trim than selected.

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 P0131 or P0151

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	If DTCs P2251 or P2254 are also set, diagnose those DTCs first. Is DTC P2251 or P2254 also set?	-	Go to DTC P2251 or P2254	Go to Step 3
3	Start the engine. Allow the engine to reach operating temperature. Refer to Scan Tool Data List . Cycle the throttle from idle to wide open throttle (WOT) 3 times within 5 seconds. Observe the HO2S Bank 1 Sensor 1 or HO2S Bank 2 Sensor 1 parameter with a scan tool. Does the affected lambda value react immediately to the above action?	-	Go to Step 4	Go to Step 5
4	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 5	Go to Intermittent Conditions
5	Turn OFF the ignition. Inspect the exhaust system for any leaks upstream from the affected heated oxygen sensor (HO2S). Inspect for any exhaust leaks between the HO2S 1 and the HO2S 2. Repair the exhaust leak as necessary. Refer to Exhaust Leakage in Engine Exhaust. Did you find and correct the condition?	-	Go to Step 22	Go to Step 6
6	Disconnect the connector for the HO2S 1 that applies to this DTC. Visually and physically inspect for the following items: The HO2S 1 is securely installed. Terminal corrosion or water intrusion Terminal tension at the HO2S 1 connectors Damaged wiring Repair as necessary. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 7
7	Turn ON the ignition, with the engine OFF. Observe the HO2S Bank 1 Sensor 1 or HO2S Bank 2 Sensor 1 parameter with a scan tool. Does the lambda value exceed the specified value?	1.115	Go to Step 12	Go to Step 8
8	Measure the voltage from the HO2S reference voltage circuit on the engine harness side connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage less than the specified value?	500 mV	Go to Step 13	Go to Step 9
9	Measure the voltage from the HO2S low reference circuit on the engine harness side connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage less than the specified value?	500 mV	Go to Step 14	Go to Step 10
10	Connect a 3-amp fused jumper wire between the HO2S low reference circuit and the HO2S reference voltage circuit on the engine harness side. Measure the voltage from the HO2S output pump current circuit on the engine harness side connector to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Is the voltage less than the specified value?	500 mV	Go to Step 15	Go to Step 11
11	Turn OFF the ignition. IMPORTANT: Disconnecting the engine control module (ECM) may eliminate a circuit short. Disconnect the ECM. Test for continuity between any circuits of the affected HO2S and all other circuits of the affected HO2S. Is the resistance between any HO2S circuit and all other HO2S circuits less than the specified value?	infinity	Go to Step 19	Go to Step 16
12	Test the HO2S input pump current circuit for a short to ground. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 18
13	Test the HO2S reference voltage circuit for a short to ground. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 18
14	Test the HO2S low reference circuit for a short to ground. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 18
15	Test the HO2S output pump current circuit for a short to ground. Refer to Circuit Testing , Wiring Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 18
16	The HO2S may be detecting a lean exhaust condition. Inspect for one of the following conditions: HO2S connector water intrusion A silicon-contaminated HO2S Incorrect fuel pressure-Refer to Fuel System Diagnosis . Lean fuel injectors An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Fuel contamination-Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust to be indicated. Excessive alcohol in the fuel can also cause this condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (W/Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (W/O Special Tool) for the proper procedure for inspecting for contaminants. An inaccurate mass air flow (MAF) sensor Repair any of the above or similar engine conditions, as necessary. Did you find and correct the condition?	-	Go to Step 22	Go to Step 17
17	Test for poor connections and shorted terminals at the affected HO2S. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 20
18	Test for poor connections and shorted terminals at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 21
19	Repair the short between the affected HO2S circuits. Refer to Wiring Repairs and Heated Oxygen Sensor Wiring Repairs in Wiring Systems. Did you complete the repair?	-	Go to Step 22	-
20	Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 . Did you complete the replacement?	-	Go to Step 22	-
21	Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 22	-
22	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 23
23	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 in Vehicle DTC Information	System OK