P2272
DTC P2270 or P2272
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P2270
- HO2S Signal Stuck Lean Bank 1 Sensor 2
DTC P2272
- HO2S Signal Stuck Lean Bank 2 Sensor 2
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,275 mV. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.
Conditions for Running the DTC
* DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.
* The ignition 1 voltage is between 10-18 volts.
* The engine run time is greater than 5 minutes.
* The engine speed is between 1,100-2,500 RPM.
* The mass air flow (MAF) is between 3-20 g/s.
* The vehicle speed is between 50-120 km/h (31-75 mph).
* The fuel level is greater than 10 percent.
* The fuel system is in Closed Loop.
* The catalytic converter temperature is between 550-900°C (1,022-1,652°F).
* The DTCs run once per ignition cycle when the above conditions are met.
Conditions for Setting the DTC
P2270
The ECM does not detect a HO2S voltage greater than 805 mV before accumulated mass air flow exceeds 550 grams.
P2272
The ECM does not detect a HO2S voltage greater than 775 mV before the accumulated mass air flow exceeds 82 grams.
Action Taken When the DTC Sets
DTCs P2270 and P2272 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P2270 and P2272 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
* Heated Oxygen Sensor Wiring Repairs (Heated Oxygen Sensor Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify that no B52 HO2S heater DTCs are set.
• If any B52 HO2S heater DTCs are set, perform those diagnostics first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).
2. Engine idling, move the appropriate B52 HO2S 2 harness connector and the engine control module (ECM) harness connector while monitoring the B52 HO2S 2 voltage parameter with a scan tool. Verify that the B52 HO2S parameter does not change abruptly while moving the related harnesses.
• If the B52 HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
3. Engine idling at operating temperature, observe the appropriate B52 HO2S 2 parameter with a scan tool. Verify the following:
* The B52 HO2S 1 value should vary from below 200 mV to above 800 mV and respond to fueling changes.
* The B52 HO2S 2 should fluctuate at less than 380 mV or greater than 520 mV. The values should not remain within 380 mV and 520 mV.
4. 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
Note: All modules must be powered down or misdiagnosis may result.
1. Ignition OFF, disconnect the harness connector at the appropriate B52 HO2S.
2. Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohm between the low reference circuit terminal A and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, verify the appropriate scan tool B52 HO2S parameter is approximately 450 mV.
• If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
• If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool HO2S parameter is less than 60 mV.
• If greater than the specified range, test the signal circuit for an open/high resistance. If the circuits test normal, replace the ECM.
5. Verify none of the following conditions exist:
* Lean fuel injectors-Refer to Fuel Injector Diagnosis (J39021 or Tech 2) (Fuel Injector Diagnosis (J39021 or Tech 2))Fuel Injector Diagnosis (CH47976) (Fuel Injector Diagnosis (CH 47976))
* Water intrusion in the B52 HO2S harness connector
* Low fuel system pressure-Refer to Fuel System Diagnosis (Fuel System Diagnosis)
* Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (Special Tool) (Alcohol/Contaminants-In-Fuel Diagnosis (Special Tool))Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) (Alcohol/Contaminants-In-Fuel Diagnosis (Without Special Tool))
* Exhaust leaks near the B52 HO2S
* Engine vacuum leaks
* Contaminated B52 HO2S - Silicon
* An engine mechanical condition- Symptoms - Engine Mechanical (Symptoms - Engine Mechanical)
• If you find any of the above conditions, repair as necessary.
6. If all circuits test normal, replace the appropriate B52 HO2S.
Repair Instructions
Caution: Refer to Heated Oxygen Sensor Resistance Learn Reset Caution (Heated Oxygen Sensor Resistance Learn Reset Caution).
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (Heated Oxygen Sensor Replacement - Bank 1 Sensor 2)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (Heated Oxygen Sensor Replacement - Bank 2 Sensor 2)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming