GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Regal 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC P0133, P0134, P0140, P1133, 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 P2A00: HO2S Circuit Closed Loop (CL) Performance Sensor 1

DTC P2A01: HO2S Circuit Sensor 2

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0131, P0132, P0137, P0140, P1133, P2A00, P2A01

P0131, P0132, P0133, P0134, P0137, P0140, P1133, P2A00, P2A01

P0131, P0132, P0133, P0134, P0137, P0140, P1133, P2A00, P2A01

P0132, P0134, P0138, P0140, P1133, P2A00, P2A01

P0133, P0134, P0140, P1133, P2A00

HO2S Low Signal

P2A00, P2A01

P0131, P0132, P0133, P0134, P0138, P0140, P1133, P2A00, P2A01

P0131, P0132, P0133, P0134, P0138, P0140, P1133, P2A00, P2A01

P0134, P0138, P0140, P1133, P2A00, P2A01

P2A00

Typical Scan Tool Data

HO2S Sensor 1 Voltage

Circuit

Normal Range

Short to Ground

Open

Short to Voltage

HO2S High Signal

200-800 mV

0 mV

Approximately 470 mV

Approximately 1,100 mV

HO2S Low Signal

200-800 mV

455 mV

Approximately 450 mV

Approximately 445 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 engine control module (ECM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started, the ECM 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 P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1516, P2101, P2119, P2135, P2176 are not set.
    • The Engine Coolant Temperature (ECT) Sensor parameter is more than 70°C (158°F).
    • The Ignition 1 Signal parameter is between 10-18V.
    • The Fuel Level Sensor parameter is more than 10 percent.
    • The Engine Run Time parameter is more than 200 seconds.
    • The Engine Speed parameter is between 1,000-3,500 RPM.
    • The Manifold Absolute Pressure (MAP) Sensor parameter is more than 30 kPa.
    • The Mass Airflow (MAF) Sensor parameter is between 11-50 g/s.
    • The Loop Status parameter is Closed.
    • The Throttle Position (TP) Indicated Angle parameter is more than 5 percent.
    • DTC P0133 runs once per drive cycle when the above conditions are met for 2 seconds.

P0134

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1516, P2101, P2119, P2135, P2176 are not set.
    • The Engine Coolant Temperature (ECT) Sensor parameter is more than 70°C (158°F).
    • The Ignition 1 Signal parameter is between 10-18V.
    • The engine run time is more than 200 seconds.
    • DTC P0134 runs continuously when the above conditions are met.

P0140

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1516, P2101, P2119, P2135, P2176 are not set.
    • The ECT Sensor parameter is more than 70°C (158°F).
    • The Ignition 1 Signal parameter is between 10-18V.
    • The Engine Run Time parameter is more than 200 seconds.
    • The Loop Status parameter is closed.
    • DTC P0140 runs once per drive cycle when the above conditions are met.

P1133

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1516, P2101, P2119, P2135, P2176 are not set.
    • The ECT Sensor parameter is more than 70°C (158°F).
    • The Engine Speed parameter is between 1,500-3,500 RPM.
    • The Ignition 1 Signal parameter is between 10-18V.
    • The Engine Run Time parameter is more than 200 seconds.
    • The Loop Status parameter is Closed.
    • The TP Indicated Angle parameter is more than 5 percent.
    • The Fuel Level Sensor parameter is more than 10  percent.
    • The MAP Sensor parameter is more than 30 kPa.
    • The MAF Sensor parameter is between 11-50 g/s.
    • DTC P1133 runs once per drive cycle when the above conditions are met for 2 seconds.

P2A00

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1516, P2101, P2119, P2135, P2176 are not set.
    • The Engine Run Time parameter is more than 100 seconds.
    • The Engine speed parameter is between 1,000-3,400 RPM.
    • The Ignition 1 Signal parameter is between 10-18V.
    • The Mass Airflow (MAF) Sensor parameter is between 10-30 g/s.
    • The ECT Sensor parameter is more than 70°C (158°F).
    • DTC P2A00 runs continuously when the above conditions are met for 5 seconds.

P2A01 Passive Test

    • DTCs P0030, P0036, P0053, P0054, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1133, P1516, P2101, P2119, P2135, P2176, P2A00 are not set.
    • The engine is running.
    • The Engine Run Time parameter is less than 13.3 minutes.
    • DTC P2A01 runs the passive test once per drive cycle when the above conditions are met.

P2A01 Intrusive Test

    • DTCs P0030, P0036, P0053, P0054, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0443, P1133, P1516, P2101, P2119, P2135, P2176, P2A00 are not set.
    • The Engine Run Time parameter is more than 13.3 minutes.
    • The ignition 1 Signal parameter is between 10-18V.
    • The MAF sensor parameter is between 14-100 g/s.
    • The Engine Speed parameter is between 1,000-5,000 RPM.
    • The Vehicle Speed parameter is between 32-129 km/h (20-80 mph).
    • The Short Term FT parameter is between -20 and +20 percent.
    • The maximum number of intrusive attempts is less than 50.
    • DTC P2A01 runs the intrusive test once per drive cycle when the above conditions are met for 1 second.

Conditions for Setting the DTC

P0133

    • The ECM detects that the HO2S 1 rich-to-lean or lean-to-rich average response time is more than 0.1 second.
    • DTC P0133 sets within 60 seconds when the above condition is met.

P0134

    • The ECM detects that the HO2S 1 parameter is between 400-500 mV for 100 seconds.
    • The Throttle Position (TP) Indicated Angle parameter changes more than 1 percent, 3 times.
    • DTC P0134 sets within 100 seconds when the above conditions are met.

P0140

    • The ECM detects that the HO2S 2 parameter is between 425-475 mV.
    • The TP Indicated Angle parameter changes more than 1 percent 3 times.
    • DTC P0140 sets within 100 seconds when the above conditions are met.

P1133

    • The ECM detects that the HO2S 1 rich-to-lean counts, or the lean-to-rich counts are less than a calibrated value.
    • DTC P1133 sets within 60 seconds when the above condition is met.

P2A00

    • The ECM detects that the Loop Status parameter is open.
    • DTC P2A00 sets within 50 seconds when the above condition is met.

P2A01

  1. The ECM detects that the HO2S 2 did not transition below 300 mV and above 700 mV during the passive test.
  2. One of the following tests fail:

    3. Lean Intrusive Test

    • The ECM detects that the HO2S 2 is more than 300 mV for 12 seconds.
    • The HO2S 1 is less than 350 mV.

    Rich Intrusive Test

    • The ECM detects that the HO2S 2 is less than 700 mV for 12 seconds.
    • The HO2S 1 is more than 600 mV.
  3. DTC P2A01 sets within 7 minutes when the above conditions are met.

Action Taken When the DTC Sets

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

Conditions for Clearing the MIL/DTC

DTCs P0133, P0134, P0140, P1133, P2A00, P2A01 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
    •  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

Control Module References for scan tool information

Circuit/System Verification
    • If any HO2S heater DTCs are set, perform those diagnostics first.
    • Allow the engine to reach operating temperature.
    •  Engine running, observe the affected B52A or B52B HO2S parameter with a scan tool.
       - The B52A HO2S value should vary from below 200 mV to above 800 mV and respond to fueling changes.
       - The B52B HO2S 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.
    • The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination:

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

       - A silicon contaminated HO2S
       - Engine oil consumption--Refer to Oil Consumption Diagnosis.
       - Engine coolant consumption--Refer to Loss of Coolant.

Circuit/System Testing

    Note:  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 B52A or B52B HO2S.
  3. Ignition OFF, measure for less than 5Ω between the appropriate HO2S low signal circuit terminal 3 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 K20 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 K20 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 K20 ECM.
  5. Ignition ON, install a 3A fused jumper wire at the HO2S high signal circuit terminal 4. Toggle the other end of the jumper wire between the HO2S low signal circuit terminal 3 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 K20 ECM.
  6. If all circuits test normal, replace the appropriate HO2S.

Repair Instructions

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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