GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 SLS 🢒 DTC 🢒 DTC P0133, P0134, P0140, P1133, 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 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 P2A00: HO2S Performance Bank 1 Sensor 1

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

HO2S High Signal

P0131, P0132, 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, 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 1 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 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 gases. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. The control module supplies the HO2S with a reference, reference voltage or bias voltage of approximately 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 activated, 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 gases. Low HO2S voltage indicates a lean exhaust gases.

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 three-way catalytic monitor intrusive diagnostic tests is inactive.
    • The post oxygen sensor intrusive diagnostic tests is inactive.
    • The ignition 1 signal parameter is between 10-18 volts.
    • The traction control, induction, fuel, idling, exhaust gas recirculation and engine No overspeed intrusive test is inactive.
    • The EGR valve, idling, fuel inject and intake air output control is inactive
    • The Ignition 1 Signal parameter is between 10-18 volts.
    • The Oxygen sensor heater is ON.
    • The bank 1 sensor 1 DTCs is not set.
    • The heater resistance learn value is valid.
    • The misfire DTC is inactive.
    • The engine coolant temperature (ECT) sensor parameter is more than 70°C (158°F).
    • The intake air temperature (IAT) sensor is more than -40°C (-40°F).
    • The fuel level sensor parameter is more than 10 percent.
    • The engine running time parameter is more than 202 seconds.
    • The duty cycle of canister purge solenoid valve is more than 0 percent.
    • The ethanol percentage is less than 85 percent.
    • The engine speed parameter is between 1,100-2,500 RPM.
    • The BARO sensor parameter is more than 70 kPa.
    • The mass air flow (MAF) sensor parameter is between 25-40 g/s.
    • The HO2S Loop Status parameter is Closed.
    • The throttle position (TP) indicated angle parameter is more than 3 percent.
    • The Automatic Transmission is not in Neutral, Reverse or Park.
    • The transmission range chosen is not default position.
    • The barometric pressure is not default value.
    • DTC P0133 runs once per driving 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 three-way catalytic monitor intrusive diagnostic tests is inactive.
    • The post oxygen sensor intrusive diagnostic tests is inactive.
    • The ignition 1 signal parameter is between 10-18 volts.
    • The traction control, induction, fuel, idling, exhaust gas recirculation and engine no overspeed intrusive test is inactive.
    • The EGR valve, idling, fuel inject and intake air output control is inactive.
    • The engine running time is more than 101 seconds.
    • The ethanol percentage is less than 85 percent.
    • The bank 1 sensor 2 DTCs is not set.
    • 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 three-way catalytic monitor intrusive diagnostic tests is inactive.
    • The post oxygen sensor intrusive diagnostic tests is inactive.
    • The ignition 1 signal parameter is between 10-18 volts.
    • The traction control, induction, fuel, idling, exhaust gas recirculation and engine No overspeed intrusive test is inactive.
    • The EGR valve, idling, fuel inject and intake air output control is inactive.
    • The ethanol percentage is less than 85 percent.
    • The engine running time parameter is more than 101 seconds.
    • The Loop Status parameter is Closed.
    • The bank 1 sensor 2 DTCs is not set.
    • The powertrain control module runs.
    • DTC P0140 runs once per driving 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 three-way catalytic monitor intrusive diagnostic tests is inactive.
    • The post oxygen sensor intrusive diagnostic tests is inactive.
    • The ignition 1 signal parameter is between 10-18 volts.
    • The traction control, induction, fuel, idling, exhaust gas recirculation and engine No overspeed intrusive test is inactive.
    • The EGR valve, idling, fuel inject and intake air output control is inactive.
    • The ignition 1 signal parameter is between 10-18 volts.
    • The Oxygen sensor heater is ON.
    • The bank 1 sensor 1 DTCs is not set.
    • The heater resistance learn value is valid.
    • The misfire DTC is inactive.
    • The Engine Coolant Temperature (ECT) sensor parameter is more than 70°C (158°F).
    • The intake air temperature (IAT) is more than -40°C (-40°F).
    • The Fuel Level Sensor parameter is more than 10 percent.
    • The engine running time parameter is more than 202 seconds.
    • The duty cycle of canister purge solenoid valve is more than 0 percent.
    • The ethanol percentage is less than 85 percent.
    • The engine speed parameter is between 1,100-2,500 RPM.
    • The BARO sensor parameter is more than 70 kPa.
    • The mass air flow (MAF) sensor parameter is between 20-40 g/s.
    • The HO2S Loop Status parameter is Closed.
    • The throttle position (TP) indicated angle parameter is more than 3 percent.
    • The automatic transmission is not in Neutral, Reverse or Park.
    • No fuel level sensor data condition.
    • The transmission range chosen is not default position.
    • The barometric pressure is not default value.
    • DTC P1133 runs once per driving 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, 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 running 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 air flow (MAF) sensor parameter is between 3-30 g/s.
    • The ECT sensor parameter is more than 70°C (158°F).
    • Not in three-way Catalytic Protection Mode.
    • The traction control is inactive.
    • Not in Decel Fuel Cut-off Mode.
    • Not in Power Lift Enrichment Mode.
    • The bank 1 or bank 2 sensor 1 DTC is not set.
    • The throttle default actions is not set.
    • The engine metal overheat is inactive.
    • The expected oxygen sensor temperature is more than 0°C (32°F).

Conditions for Setting the DTC

P0133

    • The control module detects that the HO2S 1 rich-to-lean or lean-to-rich average response time is more than the specified value.
    • DTC P0133 is set when the above conditions are met for 60 seconds.

P0134

    • The control module detects that the HO2S 1 parameter is less than 400 mV or more than 500 mV.
    • The throttle position (TP) indicated angle parameter is more than 5 percent.
    • It occurs 480 times during the 600 tests.
    • DTCs P0134 is set when the above conditions are met.

P0140

    • The control module detects that the HO2S 2 parameter is 400-500 mV.
    • The TP indicated angle parameter is more than 5 percent for 5 times.
    • It occurs 1,200 times during the 1,500 tests.
    • DTC P0140 is set when the above conditions are met.

P1133

    • The control module detects that the HO2S 1 rich-to-lean counts, or the lean-to-rich counts are less than a specified value.
    • DTC P1133 is set when the above conditions are met for 60 seconds.

P2A00

    • The control module detects that the Loop Status parameter is open.
    • It occurs 250 times during the 300 tests.
    • DTC P2A00 is set when the above conditions are met.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC

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

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Connector End Views
    •  Engine Control Module 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

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification
    • If any HO2S DTCs are set, diagnose those DTCs first.
    • Allow the engine to reach operating temperature.
    • With the engine running, observe the affected HO2S parameter with a scan tool.
       ⇒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 the throttle 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:

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

       - Silicon Contamination of 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. Turn the ignition OFF, disconnect the scan tool and wait 60 seconds to ensure all modules are powered down.
  2. Turn the ignition OFF, disconnect the harness connector at the appropriate HO2S sensor.
  3. Ignition OFF, test for less than 5 ohms between the appropriate heated oxygen sensor low reference 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 test 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 test 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 test normal, replace the ECM.
  5. Ignition ON, install a 3-amp fused jumper wire at the HO2S high signal circuit terminal B. Secure the jumper wire between the HO2S low signal circuit terminal A and battery voltage. Verify that the appropriate scan tool HO2S parameter changes between 0 mV and approximately 1,000 mV.
    6. ⇒If the appropriate scan tool HO2S parameter does not change correctly, test the HO2S high signal circuit for an open/ high resistance. If the circuit 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 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