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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Aveo 🢒 DTC 🢒 DTC P1134

Circuit Description

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of approximately 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

The HO2S utilizes the following circuits:

    • A signal circuit
    • A low reference circuit
    • An ignition 1 voltage circuit
    • A heater control circuit

The engine control module (ECM) monitors the rich-to-lean and lean-to-rich transition time. A transition is defined as the HO2S voltage changes from above 600 mV to below 300 mV or from below 300 mV to above 600 mV. If the ECM detects that the transition time is too long, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1134 HO2S Transition Time Ratio Sensor 1

Conditions for Running the DTC
    • DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0171, P0172, P0201-P0204, P0300, P0336, P0337, P0351, P0352, P0401, P0402, P0404, P0405, P0406, P0443, P1404, P0502, P0506, and P0507 are not set.
    • The engine coolant temperature is more than 70°C (158°F).
    • The ignition 1 voltage is more than 10 volts.
    • The fuel system is in closed loop.
    • The engine run time is more than 60 seconds.
    • The engine speed is between 1,600-4,300 RPM.
    • The calculated air flow is between 9-40 g/s.
    • The evaporative emission (EVAP) purge is less than 20 percent.
    • DTC P1134 runs once per ignition cycle once the above conditions are met for 2 seconds.

Conditions for Setting the DTC
    • The ECM detects that the HO2S 1 rich-to-lean average response time is less than 90 milliseconds or lean-to-rich average response time is more than 125 milliseconds.
        Or
    • The ECM detects that the HO2S 1 rich-to-lean or lean-to-rich switches are less than 10.
        Or
    • The ECM detects that the HO2S 1 signal spends twice the amount of time in the rich region as compared to the lean region or the HO2S 1 signal spends twice the amount of time in the lean region as compared to the rich region.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the third consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the condition is present. This test may take 5-10 minutes for the diagnostic to run.

    2.

  2. An exhaust leak 6-12 inches away from the HO2S can cause a DTC to set.

    3.

  3. Certain RTV silicone gasket materials release vapors that can contaminate the HO2S. Silicone in the fuel can also cause silicone contamination. If the sensors appear contaminated by silicone, and if all the silicone sealant is a non-silicone base, advise the customer to try a different fuel company. A missing fuel filler restrictor indicates that the customer may have used leaded fuel.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Important: If any DTCs are set, except P1134, refer to those DTCs before proceeding with this diagnostic table.

  1. Allow the engine to reach the normal operating temperature.
  2. Operate the vehicle within the parameters specified in Conditions for Running the DTC.
  3. Observe the DTC information with a scan tool.

Did DTC P1134 fail this ignition cycle?

--

Go to Step 4

Go to Step 3

3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

Inspect for an exhaust leak near the heated oxygen sensor (HO2S). Refer to Symptoms - Engine Exhaust in Engine Exhaust. After you inspect the exhaust system, return to this diagnostic.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 5

5

Inspect or test for the following conditions:

    • The HO2S is securely installed.
    • Inspect for corrosion on the HO2S terminals.
    • Inspect the terminal tension at the HO2S and at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
    • Inspect the HO2S wiring for damage. Refer to Wiring Repairs in Wiring Systems.
    • Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect for the correct RTV sealant.
    • Inspect for engine oil consumption. Refer to Oil Leak Diagnosis in Engine Mechanical - 1.4L (DOHC).
    • Inspect for engine coolant consumption. Refer to Loss of Coolant in Engine Cooling.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 6

6

Replace the HO2S 1. Refer to Heated Oxygen Sensor 1 Replacement .

Did you complete the replacement?

--

Go to Step 7

--

7
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. 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.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 8

8

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK