GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Allure 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0133, P0134, P0140, P1133, P1134, P2A00, or P2A01

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

DTC P2A01: HO2S Circuit Closed Loop (CL) Performance Sensor 2

Diagnostic Fault Information

HO2S Sensor 1

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0131, P0132, P1133, P2A00

P0131, P0132, P0133, P0134, P1133, P1134, P2A00

P0131, P0132, P0133, P0134, P1133, P1134, P2A00

P0132, P0134, P1133, P1134, P2A00

P0133, P0134, P1133, P1134, P2A00

HO2S Low Signal

P2A00

P0131, P0132, P0133, P0134, P1133, P1134, P2A00

P0131, P0132, P0133, P0134, P0137, P0138, P0140, P1133, P1134, P2A00

P0134, P1133, P1134, P2A00

P2A00

HO2S Sensor 2

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0137, P0140, P2A01

P0137, P0140, P2A01

P0137, P0140, P2A01

P0138, P0140, P2A01

P0140, P2A01

HO2S Low Signal

P2A01

P0137, P0138, P0140, P2A01

P0137, P0138, P0140, P2A01

P0138, P0140, P2A01

P2A01

Typical Scan Tool Data

HO2S Sensor 1

HO2S Sensor Voltage Circuits

Normal Range

Short to Ground

Open

Short to Voltage

HO2S High Signal

50-850 mV

0-45 mV

Approximately 450 mV

Approximately 1106 mV

HO2S Low Signal

50-850 mV

50-850 mV

400-600 mV

50-850 mV

HO2S Sensor 2

HO2S Sensor Voltage Circuits

Normal Range

Short to Ground

Open

Short to Voltage

HO2S High Signal

50-850 mV

0-45 mV

Approximately 450 mV

Approximately 1106 mV

HO2S Low Signal

50-850 mV

50-850 mV

400-600 mV

50-850 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 control module supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started, the control module 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, P2119, 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 1,300-2,200 RPM.
    • The evaporative emission (EVAP) system is purging.
    • The Barometric (BARO) parameter is at least 69.8 kPa.
    • 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, P2119, 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 Engine Run Time parameter is more than 120 seconds.

P0140 - Regular Test

    • 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, P2119, 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 2 minutes.
    • The TP Indicated Angle parameter has changed more than 8 percent at least 3 times.
    • The Loop Status parameter is closed.

P0140 - Fast Pass Test

    • 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, P2119, 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:
       - The Engine Run Time parameter is less than 90 seconds.
       - OR
       - A cold start condition has been detected, identified by the following conditions:
   •  The Start-Up ECT parameter is less than 35°C (95°F).
   • The Start-Up intake air temperature (IAT) parameter is less than 35°C (95°F).
   • The difference between the Start-Up ECT parameter and the Start-Up IAT parameter is less than 6°C (10.8°F).

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, P2119, 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.
    • The 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 BARO parameter is at least 69.8 kPa.
    • The vehicle is not in Park, Reverse, or Neutral.

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, P2119, 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 3 minutes.
    • 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 8-38 g/s.
    • The Engine Speed parameter is between 602-3,000 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.

P2A01 - Passive Test

    • DTCs P0030, P0053, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0123, 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, P2119, P2135 are not set.
    • DTCs P0411, P0412, P0418, P2430, P2431, P2432, P2433, P2440, P2444 are not set, where applicable.
    • The engine is running for at least 6 seconds.
    • The ignition voltage is between 10-18 volts.

P2A01 - Intrusive Test

    • DTCs P0030, P0053, P0068, P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0123, 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, P2119, 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 more than 6 minutes.
    • The ignition voltage is between 10-18 volts.
    • The Engine Speed parameter is between 1,000-3,000 RPM.
    • The calculated MAF is between the following:
       - For L26--13-40 g/s
       - For L32--14-40 g/s
    • The Vehicle Speed parameter is between 32-128 km/h (20-80 mph).
    • When all of the above conditions have been met for at least 2.5 seconds, the following conditions must also be met:
       - The evaporative emission (EVAP) purge diagnostic is not active.
       - The Short Term FT parameter is between +4 and -4 percent.
       - The Loop Status parameter is closed.
       - The EVAP purge solenoid is greater than 0 percent.

Conditions for Setting the DTC

P0133

    • The control module 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 control module 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 381-525 mV for longer than a calibrated amount of time within the first 90 seconds of engine run time. If the fast pass test does not report a pass, then the regular test is initiated.

P0140 - Regular Test

    • During the regular test, the HO2S 2 voltage is between 390-525 mV for at least 120 seconds.
    • This diagnostic runs once per trip.

P1133 and P1134

    • The control module 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.

P2A00

    • The PCM detects that the loop status parameter is open.
    • DTC P2A00 sets within 50 seconds when the above condition is met.
    • This diagnostic runs continuously.

P2A01

    • The HO2S 2 parameter is between 290-685 mV during the passive test.
    • One of the following tests fail:

Lean Intrusive Test

       - The control module detects that the HO2S 2 voltage is more than 290 mV for 11.4 seconds.
       - The control module detects that the HO2S 1 voltage is less than 100 mV.

Rich Intrusive Test

       - The control module detects that the HO2S 2 voltage is less than 685 mV for 11.4 seconds.
       - The control module detects that the HO2S 1 voltage is more than 777 mV.
    • This diagnostic runs once per trip.

Action Taken When the DTC Sets

DTCs P0133, P0134, P0140, P1133, P1134, P2A00, and P2A01 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0133, P0134, P0140, P1133, P1134, P2A00, and P2A01 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Powertrain Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Heated Oxygen Sensor Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Output Controls

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 .

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 resistance 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 ECM.
  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 ECM.
    ⇒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 ECM.
  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 ECM.
  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