P0131
DTC P0131, P0132, P0134, P0137, P0138, or P0140
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 provide an overview of each diagnostic category.
DTC Descriptors
DTC P0131
- HO2S Circuit Low Voltage Sensor 1
DTC P0132
- HO2S Circuit High Voltage Sensor 1
DTC P0134
- HO2S Circuit Insufficient Activity Sensor 1
DTC P0137
- HO2S Circuit Low Voltage Sensor 2
DTC P0138
- HO2S Circuit High Voltage Sensor 2
DTC P0140
- HO2S Circuit Insufficient Activity 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 0-1 275 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
DTC P0131 or P0137
* DTCs P0068, P0106, P0108, P0122, P0123, P0201, P0202, P0203, P0204, P0222, P0223, P0442, P0443, P0449, P0452, P0455, P0496, P0606, P16F3 and P2101 are not set.
* The system voltage is between 10-32 V.
* The fuel level is greater than 10%.
* The fuel composition is less than 87% ethanol.
* The fuel system is in Closed Loop.
* The engine is not decelerating.
* DTC P0131 runs continuously when the above conditions are met for greater than 3 s.
* DTC P0137 runs continuously when the above conditions are met for greater than 5 s.
DTC P0132 or P0138
* DTCs P0106, P0108, P0201, P0202, P0203, P0204, P0442, P0443, P0449, P0452, P0453, P0455 and P0496 are not set.
* The system voltage is between 10-32 V.
* The fuel level is greater than 10%.
* The fuel composition is less than 87% ethanol.
* The fuel system is in Closed Loop.
* The engine runtime is greater than 5 s.
* The engine is not decelerating.
* DTC P0132 and P0138 run continuously when the above conditions are met for greater than 3 s.
DTC P0134 or P0140
* DTCs P0068, P0101, P0102, P0103, P0122, P0123, P0222, P0223, P0606 and P16F3 are not set.
* The ignition voltage is between 10-32 V.
* The heated oxygen sensor heater warm up is finished.
* The engine runtime is greater than 5 s.
* The fuel composition is less than 87% ethanol.
* DTC P0134 and P0140 run continuously when the above conditions are met.
Conditions for Setting the DTC
P0131 or P0137
The engine control module detects that the heated oxygen sensor voltage is less than 20 mV for greater than 38 s.
P0132 or P0138
The engine control module detects that the heated oxygen sensor voltage is greater than 1 050 mV for greater than 10 s.
P0134 or P0140
The engine control module detects that the heated oxygen sensor voltage is greater than 1 700 mV for greater than 10 s.
Action Taken When the DTC Sets
DTCs P0131, P0132, P0134, P0137, P0138 and P0140 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0131, P0132, P0134, P0137, P0138 and P0140 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left (D61)
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.
2. Verify no HO2S heater DTCs are set.
• If a HO2S heater DTC is set.
Refer to DTC P0030-P0032, P0036-P0038, P0053, P0054, P0135, or P0141 P0030.
• If no HO2S heater DTC is set.
3. Allow the engine to reach operating temperature, engine running.
4. Verify the scan tool HO2S Sensor 1 or 2 voltage parameters are between 50-1 050 mV.
• If not between 50-1 050 mV.
Refer to Circuit/System Testing.
• If between 50-1 050 mV.
5. 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.
6. Verify the DTC does not set.
• If the DTC sets.
Refer to Circuit/System Testing.
• If the DTC does not set.
7. All OK.
Circuit/System Testing
1. Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at the appropriate B52 Heated Oxygen Sensor. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 5 ohms between the low reference circuit terminal 3 and ground.
• If 5 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If less than 5 ohms
3. Ignition ON.
4. Test for 1.5-2.5 V between the high signal circuit terminal 4 and ground.
• If less than 1.5 V
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K20 Engine Control Module.
• If greater than 2.5 V
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF
4. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If between 1.5-2.5 V
5. Verify none of the following conditions exist:
* Lean or rich fuel injectors. Refer to Fuel Injector Diagnosis Fuel Injector Diagnosis.
* Water intrusion in the HO2S harness connector
* Low or high fuel system pressure. Refer to Fuel System Description Fuel System Description.
* Fuel that is contaminated. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Alcohol/Contaminants-in-Fuel Diagnosis.
* Fuel saturation of the evaporative emission (EVAP) canister
* Exhaust leaks near the HO2S
* Engine vacuum leaks
• If a condition is found
Repair as necessary.
• If no condition is found
Test or replace the appropriate B52 Heated Oxygen Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic repair.
* Heated Oxygen Sensor Replacement - Sensor 1 Heated Oxygen Sensor Replacement - Sensor 1
* Heated Oxygen Sensor Replacement - Sensor 2 Heated Oxygen Sensor Replacement - Sensor 2
* Perform the scan tool Heated Oxygen Sensor Resistance Learn Reset after replacing a HO2S.
* Control Module References Control Module References for ECM replacement, programming, and setup.