Service Information

Captiva

DTC P2271 or P2273 - LF1, LFW, LFX

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	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

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
HO2S High Signal	P0131, P0137, P0151, P0157	P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160	P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160	P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160	P0133, P013A, P013B, P013C, P013D, P013E, P013F, P014A, P014B, P0153, P1133, P1153, P2A00, P2A03
HO2S Low Signal	P0131, P0137, P0151, P0157	P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160	P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160	P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160	P0133, P013A, P013B, P013C, P013D, P013E, P013F, P014A, P014B, P0153, P1133, P1153, P2A00, P2A03
HO2S Heater Voltage Supply	P0030, P0036, P0050, P0056, P0132, P0135, P0138, P0141, P0152, P0155, P0158, P0161, *	P0030, P0036, P0050, P0056, P0132, P0134, P0135, P0138, P0140, P0141, P0152, P0154, P0155, P0158, P0160, P0161	P0030, P0036, P0050, P0056, P0132, P0134, P0135, P0138, P0140, P0141, P0152, P0154, P0155, P0158, P0160, P0161	P0690	P0135, P0141, P0155, P0161
HO2S Heater Control	P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0135, P0141, P0155, P0161	P0030, P0036, P0050, P0056, P0132, P0134, P0135, P0138, P0140, P0141, P0152, P0154, P0155, P0158, P0160, P0161	P0030, P0036, P0050, P0056, P0132, P0134, P0135, P0138, P0140, P0141, P0152, P0154, P0155, P0158, P0160, P0161	P0030, P0036, P0050, P0056, P0132, P0134, P0135, P0138, P0140, P0141, P0152, P0154, P0155, P0158, P0160, P0161	P0135, P0141, P0155, P0161
* Opens Fuse

Typical Scan Tool Data

HO2S Sensor 1 Voltage, HO2S Sensor 2 Voltage

Circuit	Short to Ground	Open	Short to Voltage
*Parameter Normal Range:* 200-800 mV
HO2S High Signal	0.00 V	Approximately 1.27 V	Approximately 1.27 V
HO2S Low Signal	0.00 V	Approximately 1.27 V	Approximately 1.27 V

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

•	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 voltage is between 10-32 V.

•	The engine speed is between 1,225-2,100 RPM.

•	The mass air flow (MAF) is between 4-13 g/s.

•	The vehicle speed is between 64-125 km/h (40-78 mph).

•	The fuel level is greater than 10 %.

•	The fuel system is in Closed Loop.

•	The predicted catalytic converter temperature is between 615-980°C (1,139-1,796°F).

•	The HO2S heater is ON for more than 180 s.

•	The DTCs run once per ignition cycle, during decel fuel cut-off, when the above conditions are met.

Conditions for Setting the DTC

P2271

The ECM does not detect an HO2S voltage less than 100 mV before accumulated mass air flow exceeds 36 grams.

P2273

The ECM does not detect an HO2S voltage less than 100 mV before the accumulated mass air flow exceeds 36 grams.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

•	Heated Oxygen Sensor Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the DTC information with a scan tool. Verify no B52 HO2S heater DTCs are set.

⇒	If a B52 HO2S heater DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Engine running, observe the appropriate scan tool B52 HO2S voltage parameter. The reading should be within the range of 50-1,050 mV.
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

Ignition OFF, disconnect the appropriate B52 HO2S harness connector.
Ignition ON, observe the appropriate scan tool HO2S voltage parameter. The parameter should display 1.27 V.

⇒	If less than the specified range, test the high and low signal circuits for a short to ground. If both signal circuits test normal, replace the K20 ECM.

Ignition ON, test for 2.5-3.0 V 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.

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 0.90-1.10 V on the low signal circuit is normal.

Ignition ON, verify the scan tool HO2S parameter displays 0.0 V.

⇒	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.

If all circuits test normal, test or replace the appropriate B52 HO2S.

Repair Instructions

Caution: Refer to Heated Oxygen Sensor Resistance Learn Reset Caution in the Preface section.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 : LF1 or LFW

•	Heated Oxygen Sensor Replacement - Bank 2 Sensor 2

•	Control Module References for ECM replacement, setup, and programming