Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: This step determines if a condition exists.
5: This step is testing for a rear HO2S sensor circuit condition. A circuit condition sets this DTC.
8: This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S 2 circuits for an intermittent circuit condition.

DTC P2271

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module 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	Allow the engine to reach operating temperature. Operate the vehicle within the parameters specified in Conditions for Running the DTC. Observe the diagnostic trouble code (DTC) information with a scan tool. Did DTC P2271 fail this ignition?	-	Go to Step 4	Go to Step 3
3	Observe the Freeze Frame and/or the Failure records data for this DTC. Turn the ignition OFF 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 and/or the Failure records data. Does the DTC fail this ignition cycle?	-	Go to Step 4	Go to Diagnostic Aids
4	Is DTC P0137, P0138, or P0140 also set?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 5
5	Operate the engine above 1,200 RPM for 30 seconds. Observe the HO2S 2 voltage parameter with a scan tool. Is the voltage less than the specified value?	1,050 mV	Go to Step 8	Go to Step 6
6	Turn OFF the ignition. Disconnect the heated oxygen sensor (HO2S) 2. Turn ON the ignition with the engine OFF. Observe the HO2S 2 voltage parameter with a scan tool. Is the voltage within the specified range?	350-550 mV	Go to Step 12	Go to Step 7
7	Test the HO2S 2 signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 17	Go to Step 13
8	Move the related HO2S 2 harnesses between the HO2S harness connector and the engine control module (ECM) while monitoring the HO2S 2 voltage parameter with a scan tool. Does the HO2S parameter change abruptly while moving the related harnesses?	-	Go to Step 14	Go to Step 9
9	Turn OFF the ignition. Disconnect the HO2S 2. Inspect the HO2S 2 for the following conditions: For damaged wiring between the HO2S and the ECM-An intermittent circuit condition may cause this DTC to set. For terminal corrosion or water intrusion in the HO2S harness connector For the correct terminal tension The HO2S is securely installed. For any exhaust leaks-Refer to Symptoms - Engine Exhaust . Repair as necessary. Refer to Wiring Repairs . Did you find and correct the condition?	-	Go to Step 17	Go to Step 10
10	Inspect for the following conditions: Inspect for a collapsed air intake duct. Inspect for a restricted air filter element. Refer to Air Cleaner Element Replacement . Inspect the mass air flow (MAF) sensor for foreign objects. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Inspect for excessive fuel in the crankcase. Change the oil as necessary. Inspect for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/Special Tool) . Inspect the engine control grounds for being clean, tight, and in the correct locations. Inspect for an engine mechanical condition. Refer to Symptoms - Engine Mechanical . Did you find and correct the condition?	-	Go to Step 17	Go to Step 11
11	IMPORTANT: When you have completed the fuel system diagnosis, return to this diagnostic. Test the fuel system for operating rich. Refer to Fuel System Diagnosis .Did you find and correct the condition?	-	Go to Step 17	Go to Step 12
12	Test for shorted terminals and for 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 17	Go to Step 15
13	Test for shorted terminals and for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 17	Go to Step 16
14	Repair the circuit as necessary. Refer to Wiring Repairs . Did you complete the repair?	-	Go to Step 17	-
15	Replace the HO2S 2. Refer to Heated Oxygen Sensor 2 Replacement . Did you complete the replacement?	-	Go to Step 17	-
16	Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 17	-
17	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 18
18	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