P2270
DTC P2270 or P2272 (Heavy Duty L96)
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 0-1,000 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 voltage is between 10-32 volts.
* The engine run time is greater than 100 s.
* 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 64-132 km/h (40-82 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 or P2272
The ECM does not detect a HO2S voltage greater than 825 mV before accumulated mass air flow exceeds a calibrated value.
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.
Diagnostic Aids
This ECM uses a bias voltage on the high and low signal circuits of the HO2S. The voltage measured between the high and low signal HO2S terminals is approximately 1,900 mV. The voltage measured between the low signal HO2S terminal and ground varies based on the temperature of the HO2S and will typically be between 0 and 1,000 mV, under normal operating conditions. The value of the high signal circuit when measured to ground will be approximately equal to the voltage measured between ground and the low signal circuit plus 1,900 mV.
Reference Information
Schematic Reference
Engine Controls Schematics (except L96) [1][2]Electrical DiagramsEngine Controls Schematics (L96) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify that no HO2S heater DTCs are set.
• If any 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 running, observe the appropriate scan tool B52 HO2S voltage parameter. The reading should vary between 50-1,050 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. Ignition OFF, disconnect the harness connector at the appropriate B52 HO2S.
2. Ignition ON, observe the appropriate scan tool HO2S voltage parameter. The parameter should display 1,900 mV.
• If less than the specified range, test the high and low signal circuits for a short to ground. If both signal circuit test normal, replace the K20 ECM.
3. Ignition ON, test for 1,900-3,000 mV between the high signal circuit terminal B and ground.
• If less than the specified range, test the high signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
4. Ignition OFF, connect a 3 A fused jumper wire between the high signal circuit terminal B and the low signal circuit terminal A.
Note: The low signal circuit is tied to a pull-up circuit within the ECM. A voltage of 900-,100 mV on the low signal circuit is normal.
5. Ignition ON, verify the scan tool HO2S parameter displays 0.0 mV.
• If greater than the specified range, test the low signal circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
6. If all circuits test normal, replace the appropriate B52 HO2S.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis) Service and RepairHeated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series) Service and RepairHeated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series) Service and Repair
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis) Service and RepairHeated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series) Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series) Service and Repair
* Perform the scan tool Heated Oxygen Sensor Resistance Learn Reset after replacing a HO2S.
* Control Module References Control Module References for ECM replacement, setup, and programming