GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 Firebird 🢒 Engine 🢒 Engine Controls - 5.7L 🢒 DTC P0134 or P0154

Circuit Description

The powertrain control module (PCM) supplies a voltage of approximately 450 mV between the heated oxygen sensor (HO2S) high and low signal circuits. The heated oxygen sensor varies the voltage from approximately 1,000 mV when the exhaust is rich, to approximately 10 mV when the exhaust is lean.

The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the time that the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period, and determines if the majority of the samples are out of the operating range.

The PCM monitors the HO2S voltage and detects if the voltage goes out of the bias range. If the PCM does not detect that the voltage went out of the bias range, a DTC sets.

Conditions for Running the DTC
    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0200, P0300, P0410, P0440, P0442, P0446, P0452, P0453, P1258, P1415, P1416, or P1441 are not set.
    • The ignition 1 signal is between 9-18 volts.
    • The secondary air injection (AIR) and the catalyst diagnostics are not active.
    • The loop status is Closed.
    • The engine run time is more than 409 seconds.

Conditions for Setting the DTC
    • The HO2S signal voltage remains between 350-550 mV.
    • The conditions are present for 57 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second 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 3 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. Before you perform this test, the engine must be at the normal operating temperature.

    2.

  2. The Freeze Frame/Failure Records data may help to locate an intermittent condition. If you cannot duplicate the DTC, the information in the Freeze Frame/Failure Records data can help to determine how many miles have occurred since the DTC set. The Fail Counter and the Pass Counter can also help to determine the number of ignition cycles during which the diagnostic reported a pass and/or a fail. In order to isolate when the DTC failed, operate the vehicle within the same Freeze Frame conditions that the PCM recorded. These conditions include the RPM, the vehicle load, the vehicle speed, and the temperature.

    3.

  3. If the scan tool indicates the HO2S voltage goes below 200 mV, the HO2S circuits and PCM are OK.

    4.

  4. This step verifies whether the signal circuit from the PCM is OK.

    5.

  5. This step verifies whether the low signal circuit from the PCM is OK. A voltage indicates the PCM and wiring are OK.

    6.

  6. Disconnecting the PCM allows using a DMM in order to test the circuit continuity. This procedure helps to locate a circuit that is open or shorted.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Important: Before you proceed with this DTC, inspect the HO2S for being secure. A loose sensor can cause this DTC to set.

  1. Install a scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Operate the engine above 1200 RPM for 2 minutes.
  4. Use a scan tool in order to observe the HO2S voltage.

Does the scan tool indicate the HO2S voltage varies outside the specified range?

350-550 mV

Go to Step 3

Go to Step 4

3

  1. Observe the Freeze Frame/Failure Records data 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 as specified in the supporting text or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn ON the ignition, with the engine OFF.
  2. Disconnect the affected HO2S.
  3. Jumper the HO2S high signal circuit to a known good ground.
  4. Jumper the HO2S low signal circuit to a known good ground.
  5. Use a scan tool in order to observe the HO2S voltage.

Is the HO2S voltage below the specified value?

200 mV

Go to Step 8

Go to Step 5

5

  1. Remove both jumper wires.
  2. Measure the voltage from the HO2S low signal circuit to a battery ground using the DMM.

Does the DMM indicate that the voltage is near the specified value?

5 V

Go to Step 6

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1, located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement .
  3. Test the continuity of the HO2S high signal circuit. Refer to Testing for Continuity in Wiring Systems.
  4. Repair the open circuit if no continuity is indicated on the DMM. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1, located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement .
  3. Test the continuity of the HO2S low signal circuit. Refer to Testing for Continuity in Wiring Systems.
  4. If the DMM indicates no continuity, repair the open connection or the poor connection. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

8
  1. Inspect the HO2S circuits for a poor connection at the HO2S harness connector.
  2. If you find a poor connection, repair the connection as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 12

Go to Step 9

9

Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 and/or heated oxygen sensor (HO2S) replacement bank 2 sensor 1.

Did you complete the replacement?

--

Go to Step 12

--

10
  1. Inspect the HO2S circuits for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the connection as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

11

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Use a scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 13

Go to Step 2

13

With scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK