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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2001 🢒 Aurora 🢒 Engine 🢒 Engine Controls - 4.0L 🢒 DTC P0154

Circuit Description

The heated oxygen sensor (HO2S) is a sensor used in order to detect the oxygen content in the exhaust. The powertrain control module (PCM) supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal. The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, the PCM adjusts the injector pulse width.

Conditions for Running the DTC
    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201-P0208, P0410, P0440, P0442, P0443, P0446, P0449, P1415, P1416, or P1441 are not set.
    • The system voltage is between 9-18 volts.
    • The engine is running for 3 minutes.
    • The exhaust gas recirculation (EGR) flow diagnostic test is not active.
    • The catalyst diagnostic test is not active.
    • The secondary air injection (AIR) diagnostic test is not active.

Conditions for Setting the DTC

The HO2S bank 2 sensor 1 signal voltage remain within 400-500 mV for approximately 80 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.

Diagnostic Aids

Notice: Do not solder heated oxygen sensor wires. Soldering the wires will result in the loss of the air reference to the sensor. Refer to Engine Electrical for proper wire and connection repair techniques.

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

   • The PCM harness connectors
   • The electrical center fuse/relay cavities
   • The component terminals
   • The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.

Check for the following conditions:

    • Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • A damaged harness--Inspect the wiring harness for damage. If the harness appears OK, observe the scan tool while moving connectors and wiring harnesses that are related to HO2S bank 2 sensor 1. A change in the display will indicate the location of the malfunction. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • For intermittent conditions, refer to Symptoms - Engine Controls .
        Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help determine how often the condition that set the diagnostic trouble code (DTC) occurs.

Test Description

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

  1. When the system is operating correctly, the HO2S voltage should toggle above and below the specified values.

    2.

  2. The specified value is what is measured on a correctly-operating system.

    3.

  3. The specified value is what is measured on a correctly-operating system.

    4.

  4. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

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: If any other DTCs are set except the HO2S DTCs, refer to other DTCs first before proceeding with this table.

  1. Engine at operating temperature.
  2. Operate engine above 1200 RPM for 2 minutes.
  3. With a scan tool, observe the HO2S voltage parameter.

Does the voltage varying outside the specified value?

400-500 mV

Go to Step 3

Go to Step 4

3
  1. Review and record the scan tool Failure Records.
  2. Operate the vehicle within the Conditions for Running the DTC .
  3. Using the scan tool, observe the Specific DTC Information for DTC P0154 until the test runs.

Does the scan tool indicate that DTC P0154 is current?

--

Go to Step 4

Go to Diagnostic Aids

4

Inspect and test for the following conditions:

    • Exhaust leak
    • The HO2S is installed correctly
    • Damaged wiring--Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the HO2S .
  3. Turn ON the ignition.
  4. Using the DMM, measure the voltage between the HO2S high signal circuit on the PCM side and a good ground.

Does the voltage measure near the specified value?

450 mV

Go to Step 6

Go to Step 8

6

  1. Jumper the high signal circuit to the low signal circuit on the PCM side.
  2. With a scan tool, observe HO2S voltage parameter.

Does the voltage measure near the specified value?

0 mV

Go to Step 9

Go to Step 7

7
  1. Test the low signal circuit for an open or for high resistance. Refer to Circuit Testing in Wiring Systems.
  2. If the condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

8
  1. Test the high signal circuit for an open or for high resistance. Refer to Circuit Testing in Wiring Systems.
  2. If an open or a high resistance condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

9
  1. Test for poor connections at the HO2S. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a poor connection conditions is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10

Notice: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.

Important: Determine the cause of contamination before replacing the sensor.

  1. Inspect and test for the following conditions:
    2. • Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Engine oil or coolant consumption--Refer to Oil Pressure Diagnosis and Testing in Engine Mechanical.
    • Use of improper room temperature vulcanizing (RTV) sealant.
  2. Replace the HO2S . Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Did you complete the replacement?

--

Go to Step 13

--

11

Test for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

12

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 13

--

13
  1. Review and record the scan tool Failure Records.
  2. Clear the DTCs.
  3. Operate the vehicle within the Failure Record conditions.
  4. Using the scan tool, observe the Specific DTC Information for DTC P0154 until the test runs.

Does the DTC run and pass?

--

Go to Step 14

Go to Step 2

14

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

--

Go to Diagnostic Trouble Code (DTC) List

System OK