DTC P0131, P0132, or P0134 (Without LF1)
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DTC P0131, P0132, or P0134 (Without LF1)
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DTC P0131
HO2S Circuit Low Voltage Sensor 1
DTC P0132
HO2S Circuit High Voltage Sensor 1
DTC P0134
HO2S Circuit Insufficient Activity Sensor 1
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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HO2S Sensor 1 Signal
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P0131
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P0134, P0135
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P0132
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P0133, P2096, P2097
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HO2S Sensor 2 Signal
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P0137
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P0140, P0141
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P0138
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P0141
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Low Reference
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-
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P0134, P0135, P0140, P0141
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-
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-
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HO2S 1 or 2
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Circuit
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Short to Ground
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Open
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Short to Voltage
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Operating Conditions:
The engine is operating in closed loop
Parameter Normal Range:
Fluctuates above and below 350-500 mV
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Sensor Signal
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0-60 mV
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445-450 mV
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1275 mV
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Low Reference
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-
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445-480 mV
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1275 mV
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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 in 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. The control module supplies the HO2S with a reference, or bias voltage of about 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. 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 above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage 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.
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Conditions for Running the DTC
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DTC P0131 - Condition 1
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DTC P0201, P0202, P0203, P0204, P0205, P0206, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 is not set.
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The ignition voltage is greater than 11 volts.
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The engine is operating.
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The air flow into the engine is greater than 10 grams.
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The HO2S 1 heater duty cycle is greater than 70 percent for greater than 8 seconds.
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DTC P0131 runs continuously once the conditions above exist for greater than 30 seconds.
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DTC P0131 - Condition 2
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DTC P0116, P0117, P0118, P0119, P0201, P0202, P0203, P0204, P0205, P0206 P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 is not set.
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The ignition voltage is greater than 11 volts.
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The engine is operating for greater than 1 second.
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The engine coolant temperature (ECT) during the previous ignition cycle was greater than 60°C (140°F).
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The ECT at startup is less than 40°C (104°F).
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The HO2S 1 heater duty cycle is greater than 70 percent for greater than 8 seconds.
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DTC P0131 runs continuously once the conditions above exist.
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DTC P0132
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DTC P0201, P0202, P0203, P0204, P0205, P0206, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 is not set.
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The ignition voltage is greater than 10 volts.
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The engine is operating.
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The HO2S 1 heater duty cycle is greater than 70 percent for greater than 8 seconds.
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DTC P0132 runs continuously once the conditions above exist for greater than 5 seconds.
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DTC P0134
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DTC P0131, P0201, P0202, P0203, P0204, P0205, P0206, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 is not set.
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The ignition voltage is greater than 10 volts.
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The engine is operating.
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The HO2S 2 is at operating temperature.
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The HO2S 1 heater duty cycle is greater than 70 percent for greater than 8 seconds.
OR
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The HO2S 1 heater duty cycle is greater than 68 percent and the calculated exhaust temperature is greater than 600°C (1112°F) for more than 30 seconds.
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The air flow into the engine has exceeded 10 grams.
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DTCs P0134 runs continuously once the conditions above exist for greater than 5 seconds.
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Conditions for Setting the DTC
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DTC P0131 - Condition 1
The ECM detects that the HO2S 1 signal voltage is less than 60 mV while the corresponding HO2S 2 voltage is greater than 500 mV.
DTC P0131 - Condition 2
The ECM detects that the HO2S 1 signal voltage is less than 60 mV after a cold start with the engine coolant temperature (ECT) less than 40°C (104°F).
DTC P0132
The ECM detects that the HO2S 1 signal voltage is greater than 1,150 mV.
DTC P0134
DTC P0134 sets if any of the following conditions exist:
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An HO2S 1 signal voltage is between 400-600 mV, or 400-550 mV when the calculated exhaust temperature is greater than 800°C (1,472°F)
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The calculated internal resistance of a HO2S 1 is greater than 20,000 Ω when the calculated exhaust temperature is greater than 600°C (1112°F).
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A corresponding HO2S 1 and HO2S 2 are greater than 200 mV during a decel fuel cut-off greater than 3 seconds.
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Action Taken when the DTC Sets
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DTC P0131, P0132, and P0134 are Type B DTCs
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Conditions for Clearing the MIL/DTC
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DTC P0131, P0132, and P0134 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
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Circuit/System Verification
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1.
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Engine idling, observe the scan tool HO2S 1 voltage parameter. The voltage should fluctuate above and below the range of 350-550 mV.
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2.
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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.
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1.
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Ignition OFF, disconnect the harness connector at the B52 HO2S 1.
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2.
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Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
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3.
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If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition circuit and replace as necessary.
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4.
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Ignition OFF, connect a test lamp between the heater control circuit terminal 2 and B+.
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5.
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Idle the engine, and verify the test lamp illuminates or flashes.
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6.
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If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
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7.
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Ignition ON, verify that the scan tool HO2S 1 voltage parameter is between 350-500 mV.
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8.
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If less than the specified range, test the signal circuit terminal 4 for a short to ground. If the circuit/connections test normal, replace the K20 ECM.
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9.
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If greater than the specified range, test the signal circuit terminal 4 for a short to voltage. If the circuit/connections test normal, replace the K20 ECM.
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10.
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Connect a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool HO2S voltage parameter is less than 60 mV.
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11.
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If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
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12.
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Connect a 3 A fused jumper wire between the signal circuit terminal 4 and the low reference circuit terminal 3. Verify the scan tool HO2S voltage parameter is less than 60 mV.
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13.
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If greater than the specified range, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit/connections test normal, replace the K20 ECM.
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14.
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Verify that none of the following conditions exist:
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Water intrusion in the HO2S harness connector
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Fuel saturation of the evaporative emission (EVAP) canister
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Exhaust leaks near the HO2S
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If you find any of the above conditions, repair as necessary.
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15.
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If all circuits/connections test normal, replace the B52 HO2S 1.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
