DTC P2270 or P2272 without LLT

Diagnostic Instructions

DTC Descriptors

DTC P2270: HO2S Signal Stuck Lean Bank 1 Sensor 2

DTC P2272: HO2S Signal Stuck Lean Bank 2 Sensor 2

Circuit Description

The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range. The ECM test for the following conditions:

Conditions for Running the DTC

Conditions for Setting the DTC

The ECM detects that the HO2S 2 voltage is less than 630 mV for greater than 100 seconds, then an intrusive test is performed. The ECM will enrich the fuel mixture 2 percent per second and then wait for 10 seconds at 20 percent. If the ECM detects that the HO2S 2 voltage is still less than 630 mV during the intrusive test, for greater than 4 second or for a cumulative of 30 seconds the DTC sets.

Action Taken when the DTC Sets

DTCs P2270 and P2272 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2270 and P2272 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0137, P0138, P0140, P0157, P0158, or P0160 is not set.

⇒	If any of the listed DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. Operate the engine above 1,200 RPM for 30 seconds, observe the HO2S voltage parameter. The reading should fluctuate above and below the range of 401-519 mV.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Engine operating, move the related HO2S harnesses for the appropriate HO2S 2 between the HO2S harness connector and the engine control module (ECM) while monitoring the appropriate scan tool HO2S voltage parameter. Verify that the HO2S parameter does not change abruptly while moving the related harnesses.

⇒	If the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.

2. Ignition OFF, disconnect the harness connector at the appropriate HO2S 2.
3. Ignition ON, verify that the scan tool HO2S 2 parameter is between 401-519 mV.

⇒	If less than the specified range, test the signal circuit terminal B for a short to ground. If the circuit/connections test normal, replace the ECM.

4. Verify that none of the following conditions exist:

•	The vacuum hoses for splits, kinks, and proper connection

•	The air intake system after the mass air flow (MAF) sensor for vacuum leaks

•	Exhaust system leaks

•	Lean fuel injectors--Refer to Fuel Injector Solenoid Coil Test.

•	Water intrusion in the HO2S harness connector

•	Low fuel system pressure--Refer to Fuel System Diagnosis.

•	Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis.

•	Contaminated HO2S - Silicon

•	An engine mechanical condition--Refer to Symptoms - Engine Mechanical.

⇒	If you find any of the above conditions, repair as necessary.

5. If all circuits/connections test normal, replace the appropriate HO2S.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC P2270 or P2272 w/LLT

Diagnostic Instructions

DTC Descriptors

DTC P2270: HO2S Signal Stuck Lean Bank 1 Sensor 2

DTC P2272: HO2S Signal Stuck Lean Bank 2 Sensor 2

Circuit Description

The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) high signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. The ECM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range. The ECM test for the following conditions:

Conditions for Running the DTC

Conditions for Setting the DTC

The ECM detects that the HO2S 2 voltage is less than 629 mV for greater than 100 seconds, then an intrusive test is performed. The ECM will enrich the fuel mixture 2 percent per second and then wait for 10 seconds at 20 percent. If the ECM detects that the HO2S 2 voltage is still less than 629 mV during the intrusive test, for greater than 4 second or for a cumulative of 30 seconds the DTC sets.

Action Taken when the DTC Sets

DTCs P2270 and P2272 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2270 and P2272 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0137, P0138, P0140, P0157, P0158, or P0160 is not set.

⇒	If any of the listed DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. Operate the engine above 1,200 RPM for 30 seconds, observe the HO2S voltage parameter. The reading should fluctuate above and below the range of 401-519 mV.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Engine operating, move the related HO2S harnesses for the appropriate HO2S 2 between the HO2S harness connector and the engine control module (ECM) while monitoring the appropriate scan tool HO2S voltage parameter. Verify that the HO2S parameter does not change abruptly while moving the related harnesses.

⇒	If the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.

2. Ignition OFF, disconnect the harness connector at the appropriate HO2S 2.
3. Ignition ON, verify that the scan tool HO2S 2 parameter is between 401-519 mV.

⇒	If less than the specified range, test the signal circuit terminal B for a short to ground. If the circuit/connections test normal, replace the ECM.

4. Verify that none of the following conditions exist:

•	The vacuum hoses for splits, kinks, and proper connection

•	The air intake system after the mass air flow (MAF) sensor for vacuum leaks

•	Exhaust system leaks

•	Lean fuel injectors--Refer to Fuel Injector Solenoid Coil Test.

•	Water intrusion in the HO2S harness connector

•	Low fuel system pressure--Refer to Fuel System Diagnosis.

•	Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis.

•	Contaminated HO2S - Silicon

•	An engine mechanical condition--Refer to Symptoms - Engine Mechanical.

⇒	If you find any of the above conditions, repair as necessary.

5. If all circuits/connections test normal, replace the appropriate HO2S.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.