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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 XLR 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC P0133, P0134, P0140, P1133, P2270, P2271, 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 Bank 1 Sensor 1

DTC P0134: HO2S Circuit Insufficient Activity Bank 1 Sensor 1

DTC P0140: HO2S Circuit Insufficient Activity Bank 1 Sensor 2

DTC P1133: HO2S Insufficient Switching Bank 1 Sensor 1

DTC P2270: HO2S Signal Stuck Lean Bank 1 Sensor 2

DTC P2271: HO2S Signal Stuck Rich Bank 1 Sensor 2

DTC P2A00: HO2S Performance Bank 1 Sensor 1

DTC P2A01: HO2S Performance Bank 1 Sensor 2

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0131, P0134, P0137, P0140, P0151, P0154, P0157, P0160, P1133, P1153, P2A00, P2A01, P2A03, P2A04

P0131, P0133, P0134, P0137, P0140, P0151, P0153, P0154, P0157, P0160, P1133, P1153, P2A00, P2A01, P2A03, P2A04

P0131, P0133, P0134, P0137, P0140, P0153, P0154, P1133, P1153, P2A00, P2A01, P2A03, P2A04

P0132, P0134, P0138, P0140, P0152, P0154, P0158, P0160, P1133, P1153, P2A00, P2A01, P2A03, P2A04

P0133, P0134, P0140, P0153, P0160, P1133, P1153, P2270, P2271, P2A00, P2A01, P2A03, P2A04

HO2S Low Signal

P2A00, P2A01, P2A03, P2A04

P0131, P0133, P0134, P0138, P0140, P0151, P0153, P0154, P0157, P0160, P1133, P1153, P2A00, P2A01

P0131, P0133, P0134, P0138, P0140, P0153, P0154, P1133, P1153, P2A00, P2A01, P2A03, P2A04

P0134, P0138, P0140, P0152, P0153, P0158, P0160, P1133, P1153, P2A00, P2A01, P2A03, P2A04

P2A00, P2A01, P2A03, P2A04

Typical Scan Tool Data

HO2S Sensor Voltage

Circuit

Short to Ground

Open

Short to Voltage

Parameter Normal Range: 200-800 mV

HO2S High Signal

0 mV

Approximately 470 mV

Approximately 1,100 mV

HO2S Low Signal

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, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, 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 10-18 volts.
    • The Fuel Level Sensor parameter is more than 10 percent.
    • The Engine Run Time parameter is more than 202 seconds.
    • The Engine Speed parameter is between 1,100-2,500 RPM.
    • The BARO Sensor parameter is more than 70 kPa.
    • The Mass Airflow (MAF) Sensor parameter is between 20-40 g/s.
    • The Loop Status parameter is Closed.
    • The Throttle Position (TP) Indicated Angle parameter is more than 3 percent.
    • DTC P0133 runs once per drive cycle when the above conditions are met for 1 second.

P0134

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, P1516, P2101, P2119, P2135, P2176 are not set.
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The engine run time is more than 101 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, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, P1516, P2101, P2119, P2135, P2176 are not set.
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The Engine Run Time parameter is more than 101 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, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, 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 1,100-2,500 RPM.
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The Engine Run Time parameter is more than 202 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 BARO parameter is more than 70 kPa.
    • The MAF Sensor parameter is between 20-40 g/s.
    • DTC P1133 runs once per drive cycle when the above conditions are met for 1 second.

P2270

    • DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The Engine Run Time parameter is more than 5 minutes.
    • The Engine Speed parameter is between 1,100-2,500 RPM.
    • The MAF Sensor parameter is between 3-20 g/s.
    • The Vehicle Speed parameter is between 50-120 km/h (31-75 mph).
    • The Fuel Level Sensor parameter is more than 10 percent.
    • The Loop Status parameter is closed.
    • The Catalytic Converter Temperature parameter is between 550-900°C (1,022-1,652°F).
    • DTC P2270 runs once per drive cycle when the above conditions are met.

P2271

    • DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The Engine Speed parameter is between 500-5,000 RPM.
    • The MAF Sensor parameter is between 3-50 g/s.
    • The Vehicle Speed parameter is between 24-132 km/h (15-82 mph).
    • The Fuel Level Sensor parameter is more than 10 percent.
    • The Loop Status parameter is closed.
    • DTC P2270 runs once per drive cycle when the above conditions are met for 1 second.

P2A00

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, P1516, P2101, P2119, P2135, P2176 are not set.
    • The Engine Run Time parameter is more than 100 seconds.
    • The Engine speed parameter is between 500-5,000 RPM.
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The Mass Airflow (MAF) Sensor parameter is between 3-30 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, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, P1133, P1516, P2101, P2119, P2135, P2176, P2A00 are not set.
    • The engine is running.
    • The Engine Run Time parameter is less than 260 seconds.
    • DTC P2A01 Passive Test runs the passive test once per drive cycle when the above conditions are met for 2 seconds.

P2A01 Intrusive Test

    • DTCs P0030, P0036, P0053, P0054, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1101, P1133, P1516, P2101, P2119, P2135, P2176, P2A00 are not set.
    • The Engine run Time parameter is more than 260 seconds.
    • The ignition 1 Signal parameter is between 10-18 volts.
    • The MAF sensor parameter is between 0.5-50 g/s.
    • The Engine Speed parameter is between 500-5,000 RPM.
    • The Vehicle Speed parameter is between 24-145 km/h (20-80 mph).
    • The Short Term FT parameter is between +5 and -5 percent.
    • DTC P2A01 Intrusive Test 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 0.14 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.
    • The Throttle Position (TP) Indicated Angle parameter changes more than 5 percent.
    • DTC P0134 sets within 101 seconds when the above conditions are met.

P0140

    • The ECM detects that the HO2S 2 parameter is between 400-500 mV.
    • The TP Indicated Angle parameter changes more than 5 percent 5 times.
    • DTC P0140 sets within 101 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.

P2270

    • The ECM detects that the HO2S 2 voltage oscillations are slower than a calibrated value.
    • DTC P2270 sets within 4 seconds when the above condition is met continuously, or within 50 seconds when the above condition is met cumulatively.

P2271

    • The ECM detects that the HO2S 2 voltage oscillations are faster than a calibrated value.
    • DTC P2271 sets within 4 seconds when the above condition is met continuously, or within 50 seconds when the above condition is met cumulatively.

P2A00

    • The ECM detects that the Loop Status parameter is open.
    • DTC P2A00 sets within 5 seconds when the above condition is met.

P2A01

    • The ECM detects that the HO2S 2 did not transition below 299 mV and above 751 mV during the passive test.
    • One of the following tests fail once per trip/runs until pass or fail reporting:
       - Lean Intrusive Test--The ECM detects that the HO2S 2 is more than 751 mV for 8 seconds.
       - Rich Intrusive Test--The ECM detects that the HO2S 2 is less than 299 mV for 8 seconds.
    • DTC P2A01 sets within 2 minutes when the above conditions are met.
    • The ECM detects that the Loop Status parameter is open by not meeting the voltage criteria to enable Close Loop fueling.
       ⇒Voltage cannot be between 250-600 mV for 10 seconds after the O2 has seen a ready to go Closed Loop command.
    • DTC P2A01 sets within 5 seconds when the above condition is met.

Action Taken When the DTC Sets

DTCs P0133, P0134, P0140, P1133, P2270, P2271, P2A00 and P2A01 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0133, P0134, P0140, P1133, P2270, P2271, P2A00 and 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
  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. Caution: Refer to Silicon Contamination of Heated Oxygen Sensors Caution 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

    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 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

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