Orlando

DTC P0131, P0132, P0137, or P0138

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.

P0131 00 or P0137 00

The engine control module (ECM) detects that the heated Oxygen Sensor (HO2S) voltage is less than 50 mV for greater than 38 s for DTC P0131 00 or 43 s for DTC P0137 00.

P0132 00 or P0138 00

The ECM detects that the heated Oxygen Sensor (HO2S) voltage is greater than 1 050 mV for greater than 10 s.

DTCs P0131 00, P0132 00, P0137 00, and P0138 00 are Type B DTCs.

DTCs P0131 00, P0132 00, P0137 00, and P0138 00 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. Clear the DTCs with a scan tool.
2. 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 scan tool and wait 60 s to ensure all modules are powered down.
2. Ignition OFF, disconnect the B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2 harness connector.
3. Ignition OFF, measure for less than 5 Ω between B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2 low signal circuit terminal 4 and ground.

⇒	If more than the specified range, test the appropriate B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2 low signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

4. Ignition ON, test for 0.3-0.6 V between the B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2 signal circuit terminal 4 and ground.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

5. Install a 3 A fused bridging wire between the B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2 signal circuit terminal 2 and the low reference circuit terminal 4 of the appropriate B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2. Engine running, verify the scan tool HO2S 1 or HO2S 2 parameter is less than 60 mV.

⇒	If greater than the specified value, replace the K20 Engine Control Module.

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 Description .

•	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 you find any of the above conditions, repair as necessary.

7. If all circuits test normal, replace the B52A Heated Oxygen Sensor 1 or B52B Heated Oxygen Sensor 2.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.