Captiva

DTC P0134, P0140, P0154, or P0160 - LF1, LFW, LFX

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.

P0134 or P0154

P0140 or P0160

DTCs P0134, P0140, P0154, and P0160 are Type B DTCs.

DTCs P0134, P0140, P0154, and P0160 are Type B DTCs.

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

1. 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 .

2. Engine running, observe the appropriate scan tool B52 HO2S voltage parameter. The reading should be within the range of 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.

Note: All modules must be powered down or misdiagnosis may result.

1. Ignition OFF, disconnect the appropriate B52 HO2S harness connector.
2. 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.

3. 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.

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

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

⇒	If greater than the specified value, 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. Verify none of the following conditions exist:

•	Water intrusion in the HO2S harness connector

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

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

•	Fuel saturation of the evaporative emission (EVAP) canister

•	Exhaust leaks near the HO2S

•	Engine vacuum leaks

⇒	If any of the above conditions exist, repair as necessary. If all circuits test normal, test or replace the appropriate B52 HO2S.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.