* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P2271
- HO2S Signal Stuck Rich Bank 1 Sensor 2
DTC P2273
- HO2S Signal Stuck Rich Bank 2 Sensor 2
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding
air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating
elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The control module supplies the HO2S with a
reference, or bias, voltage of about 450 mV. When the engine is first started, the control module operates in Open Loop, ignoring the HO2S voltage
signal. Once the HO2S reaches operating temperature and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV
that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream. Low HO2S voltage indicates a lean exhaust
stream.
Conditions for Running the DTC
* Before the ECM can report DTC P2271, or P2273 failed, DTCs P013A, P013C, P013E, P014A, P2270, and P2272 must run and pass.
* 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 speed is between 500-5,000 RPM.
* The mass air flow (MAF) is between 3-50 g/s.
* The vehicle speed is between 24-132 km/h (15-82 mph).
* The fuel level is greater than 10 percent.
* The fuel system is in Closed Loop.
* The engine run time is equal to or more than 5 minutes.
* The accelerator pedal position (APP) is steady.
* The torque converter clutch is TCC is applied.
* The DTCs run once per ignition cycle, during decel fuel cut-off, when the above conditions are met.
Conditions for Setting the DTC
