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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC P0133, P0134, P0140, P1133, P1134, P2270, P2271, or P2A00

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 P0133: HO2S Slow Response Sensor 1

DTC P0134: HO2S Circuit Insufficient Activity Sensor 1

DTC P0140: HO2S Circuit Insufficient Activity Sensor 2

DTC P1133: HO2S Insufficient Switching Sensor 1

DTC P1134: HO2S Transition Time Ratio Bank 1 Sensor 1

DTC P2270: HO2S Signal Stuck Lean Sensor 2

DTC P2271: HO2S Signal Stuck Rich Sensor 2

DTC P2A00: HO2S Circuit Closed Loop (CL) Performance Sensor 1

Diagnostic Fault Information

HO2S Sensor 1

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0131, P0171, P1133, P2A00

P0131, P0133, P0134, P1133, P2A00

P0131, P0133, P0134, P1133, P2A00

P0132, P0134, P0172, P0300, P1133, P2A00

P0133, P0134, P1133, P2A00

HO2S Low Signal

P2A00

P0131, P0132, P0133, P0134, P1133, P2A00

P0133, P0134, P1133, P2A00

P0134, P1133, P2A00

P2A00

HO2S Sensor 2

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0137, P0140, P2270

P0137, P0140, P2271

P0137, P0140, P2271

P0138, P0140, P2271

P0140, P2271

HO2S Low Signal

--

P0137, P0138, P0140, P2270

P0137, P0138, P0140, P2270, P2271

P0138, P0140, P2270, P2271

P2270

Typical Scan Tool Data

HO2S Sensor 1

HO2S Sensor Voltage Circuits

Normal Range

Short to Ground

Open

Short to Voltage

HO2S High Signal

0-1,000 mV

0-45 mV

Approximately 450 mV

Approximately 1106 mV

HO2S Low Signal

0-1,000 mV

0-1,000 mV

0-800 mV

50-1,106 mV

HO2S Sensor 2

HO2S Sensor Voltage Circuits

Normal Range

Short to Ground

Open

Short to Voltage

HO2S High Signal

0-1,000 mV

0-45 mV

Approximately 450 mV

Approximately 1106 mV

HO2S Low Signal

0-1,000 mV

0-1,000 mV

400-600 mV

50-1,106 mV

Circuit/System Description

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started, the PCM operates in Open Loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream. Low HO2S voltage indicates a lean exhaust stream.

Conditions for Running the DTC

P0133

    • DTCs P0030, P0053, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0131, P0132, P0134, P0135, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0442, P0443, P0446, P0449, P0451, P0452, P0454, P0455, P0496, P1516, P2101, P2135 are not set.
    • The system voltage is between 10-18 volts.
    • The scan tool special functions are not active.
    • The HO2S Sensor 1 Heater command parameter is ON.
    • The ECT sensor parameter is more than 65°C (149°F).
    • The Engine Run Time parameter is more than 60 seconds.
    • The vehicle is not in Park, Reverse, or Neutral.
    • The Loop Status parameter is closed.
    • The MAF sensor parameter is between 15-29 g/s.
    • The TP Indicated Angle parameter is more than 2 percent.
    • The Engine Speed parameter is between 1,300-3,000 RPM.
    • The evaporative emission (EVAP) system is purging.
    • The above conditions have been met for one second.

P0134

    • DTCs P0030, P0053, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P1516, P2101, P2135 are not set.
    • The system voltage is between 10-18 volts.
    • The scan tool special functions are not active.
    • The Engine Run Time parameter is more than 124 seconds.

P0140

    • DTCs P0036, P0054, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P1516, P2101, P2135 are not set.
    • The system voltage is between 10-18 volts.
    • The scan tool special functions are not active.
    • This vehicle uses the following 2 methods to enable and run this diagnostic:

Fast Pass Test

The Engine Run Time parameter is less than 75 seconds.

OR

Regular Test

    • The Engine Run Time parameter is more than 2 minutes.
    • The TP Indicated Angle parameter has changed more than 8 percent at least 3 times.
    • The Loop Status parameter is closed.

P1133 and P1134

    • DTCs P0030, P0053, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0131, P0132, P0134, P0135, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0442, P0443, P0446, P0449, P0451, P0452, P0454, P0455, P0496, P1516, P2101, P2135, P2A00 are not set.
    • The system voltage is between 10-18 volts.
    • The scan tool special functions are not active.
    • The HO2S Sensor 1 Heater command parameter is ON.
    • A current misfire condition is not detected.
    • The ECT Sensor parameter is more than 65°C (149°F).
    • The Engine Run Time parameter is at least 60 seconds.
    • The EVAP purge solenoid is commanded ON.
    • The MAF sensor parameter is between 15-30 g/s.
    • The Engine Speed parameter is between 1,300-3,000 RPM.
    • The TP Indicated Angle parameter is greater than 2 percent.
    • The Loop Status parameter is closed.
    • The vehicle is not in Park, Reverse, or Neutral.

P2270

    • DTCs  P0030, P0053, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0453, P0454, P0455, P0496, P1133, P1516, P2101, P2135, P2271, P2A00 are not set.
    • The system voltage is between 10-18 volts.
    • The engine run time is more than 300 seconds.
    • The engine speed is between 625-1,750 RPM.
    • The airflow is between 3-15 g/s.
    • The Loop Status parameter is Closed.
    • The vehicle speed is between 40-137 km/h (25-85 mph)
    • The above conditions have been met for more than 1 second.
        THEN
    • The short term fuel trim is between 0.9-1.05.
    • The EVAP purge command is 0 percent for more than 4 seconds.
    • This DTC runs once per trip when all of the above conditions have been met.

P2271

    • DTCs  P0030, P0053, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0453, P0454, P0455, P0496, P1133, P1516, P2101, P2135, P2270, P2A00 are not set.
    • The system voltage is between 10-18 volts.
    • The fuel level is more than 10 percent or the fuel level data fault is active.
    • The engine run time is more than 300 seconds.
    • The decel fuel cut-off (DFCO) is active.
    • The engine speed is between 625-1,750 RPM.
    • The airflow is between 3-15 g/s.
    • The vehicle speed is between 40-137 km/h (25-85 mph).
    • The Loop Status parameter is Closed.
    • The above conditions have been met for more than 1 second.
        THEN
    • The short term fuel trim is between 0.95-1.05 g/s.
    • The EVAP purge command is 0 percent for more than 4 seconds.
    • This DTC runs once per trip when all of the above conditions have been met.

P2A00

    • DTCs  P0030, P0053, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0128, P0131, P0132, P0133, P0134, P0135, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P1133, P1516, P2101, P2120, P2122, P2123, P2135 are not set.
    • DTCs P0411, P0412, P0418, P2430, P2431, P2432, P2433, P2440, P2444 are not set, where applicable.
    • The Engine Run Time parameter is at least 100 seconds.
    • The traction control, if equipped, is not active.
    • The control module is not commanding power enrichment (PE) or Decel Fuel Cutoff modes.
    • The MAF Sensor parameter is between 5-30 g/s.
    • The Engine Speed parameter is between 500-3,000 RPM.
    • The TP Indicated Angle parameter is between 3-35 percent.
    • The ECT Sensor parameter is more than 65°C (149°F).
    • The system voltage is between 10-18 volts.
    • The exhaust gas recirculation (EGR) flow diagnostic is not active.
    • The above conditions have been met for 3 seconds.

Conditions for Setting the DTC

P0133

    • The PCM detects that the HO2S 1 rich-to-lean and lean-to-rich transition time takes longer than a calibrated value.
    • This diagnostic runs once per trip.

P0134

    • The PCM detects that the HO2S 1 signal voltage is between 382-525 mV for more than 30 seconds.
    • This diagnostic runs continuously.

P0140 - Fast Pass Test

During the fast pass, the HO2S 2 voltage is between 350-550 mV for longer than a calibrated amount of time within the first 75 seconds of engine run time. If the fast pass test does not report a pass, then the regular test is initiated.

P0140 - Regular Test

    • The Fast Pass Test has not run or has failed.
    • During the regular test, the HO2S 2 voltage is between 382-525 mV for at least 120 seconds.
    • This diagnostic runs once per trip.

P1133 and P1134

    • The PCM detects that the HO2S 1 voltage did not have enough switches from rich-to-lean and lean-to-rich during a 90 second monitoring period.
    • This diagnostic runs once per trip.

P2270

    • The PCM detects that the 02 sensor cannot achieve voltage equal to or more than 725 mV.
        AND
    • The PCM detects that the accumulated mass air flow monitored during the Stuck Lean Voltage Test is more than 500 grams.
    • This diagnostic runs once per trip.

P2271

    • The PCM detects that the O2 sensor cannot achieve voltage equal to or less than 150 mV.
        AND
    • The PCM detects that the accumulated mass air flow monitored during the Stuck Rich Voltage Test is more than 400 grams.
    • This diagnostic runs once per trip.

P2A00

    • The PCM detects that the loop status parameter is open.
    • The HO2S 1 voltage signal remains between 300-600 mV for more than 10 seconds.
    • This diagnostic runs continuously.

Action Taken When the DTC Sets

DTCs P0133, P0134, P0140, P1133, P1134, P2270, P2271, and P2A00 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0133, P0134, P0140, P1133, P1134, P2270, P2271, and P2A00 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Heated Oxygen Sensor Wiring Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  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
  1. If any HO2S heater DTCs are set, perform those diagnostics first.
  2. Allow the engine to reach operating temperature.
  3. Engine running, observe the affected HO2S parameter with a scan tool.
    4. ⇒The pre-catalyst oxygen sensors value should vary from below 200 mV to above 800 mV and respond to fueling changes.
    ⇒The post-catalyst oxygen sensors value should change more than 200 mV when the throttle is quickly cycled 3 times from closed to wide open and back to closed after running the engine at 1,500 RPM for 30 seconds.
  4. The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination.

    5. Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section.

    • A silicon contaminated HO2S
    • Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Engine oil consumption--Refer to Oil Consumption Diagnosis .
    • Engine coolant consumption--Refer to Loss of Coolant .
  5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

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

  1. Ignition OFF, disconnect the scan tool and wait 60 seconds to ensure all modules are powered down.
  2. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
  3. Ignition OFF, measure for less than 5 ohms between the appropriate HO2S low signal circuit terminal A and ground.
    4. ⇒If more than the specified range, test the appropriate HO2S low signal circuit for an open/high resistance. If the circuit tests normal, replace the PCM.
  4. Ignition ON, verify the appropriate scan tool HO2S parameter is approximately 450 mV.
    5. ⇒If more than the specified value, test the appropriate HO2S high signal circuit for a short to voltage. If the circuit tests normal, replace the PCM.
    ⇒If less than the specified value, test the appropriate HO2S high signal circuit for a short to ground. If the circuit tests normal, replace the PCM.
  5. Ignition ON, install a 3A fused jumper wire at the HO2S high signal circuit terminal B. Toggle the jumper wire between the HO2S low signal circuit terminal A and battery voltage. Verify the appropriate scan tool HO2S parameter toggles between 0 mV and approximately 1,000 mV.
    6. ⇒If the appropriate scan tool HO2S parameter does not toggle correctly, test the HO2S high signal circuit for an open/high resistance. If the circuits test normal, replace the PCM.
  6. If all circuits test normal, replace the appropriate HO2S.

Repair Instructions

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heated Oxygen Sensor 1 Replacement
    •  Heated Oxygen Sensor 2 Replacement
    •  Control Module References for replacement, setup, and programming