GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 S10 Pickup - 2WD 🢒 DTC 🢒 DTC P0141

Circuit Description

The heated oxygen sensor (HO2S) is used for post catalyst monitoring. The 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. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. Ground is provided to the heater by a ground circuit. This diagnostic will only run once per ignition cycle. If the PCM detects that HO2S 2 time to become active was too long, DTC P0141 will set.

Conditions for Running the DTC
    • DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0171, P0172, P0201-P0204, P0300, P0301-P0304, P0336, P0440, P0446, P0452, P0453, P0506, P0507, P0601, P0602, or P1441 are not set.
    • The Ignition 1 Signal parameter is more than 10 volts.
    • The Engine Run Time is less than 4.25 minutes.
    • The Fuel Level Sensor parameter is more than 10 percent.
    • The HO2S 2 parameter is between 395-490 mV at engine start-up.
    • The ECT Sensor parameter and the IAT Sensor parameter are less than 45°C (113°F), and are within 7°C (12.6°F) of each other at engine start-up.
    • The air flow calculated parameter is less than 20 g/s.

Conditions for Setting the DTC

The PCM detects that the HO2S 2 parameter remains within 150 mV of the start-up voltage for a pre-determined amount of time based on ECT and air flow.

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. As the heater warms the O2S to operating temperature, the HO2S will output a voltage in relation to the amount of oxygen in the exhaust. With the ignition ON and the engine OFF, the exhaust usually contains a high oxygen content. With the engine OFF the HO2S voltage will usually decrease from the initial, or bias, voltage due to the high oxygen content.

    2.

  2. This step checks for proper HO2S heater ignition 1 voltage and ground supply.

    3.

  3. This step checks for proper PCM and signal circuit operation.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Important: The HO2S must be cool before proceeding with a diagnosis. The ignition must remain OFF for at least one-half hour before proceeding with a diagnosis.

  1. Connect the scan tool.
  2. Set up the scan tool with the proper vehicle identification information prior to turning the ignition ON.
  3. Turn ON the ignition, with the engine OFF.
  4. As quickly as possible observe and record the HO2S voltage for the sensor that applies to this DTC.
  5. Monitor the HO2S voltage for two minutes.

Does the HO2S voltage increase or decrease from the initial voltage by at least the value specified?

150 mV

Go to Step 3

Go to Step 4

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

  1. Turn OFF the ignition.
  2. Disconnect the HO2S 2 connector.
  3. Connect a test lamp between the HO2S heater ignition 1 voltage circuit and ground circuit terminals at the engine harness side.
  4. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 6

5

  1. Disconnect the test lamp.
  2. Jumper the HO2S low signal circuit terminal to a known good ground.
  3. Jumper the HO2S high signal circuit terminal to a known good ground.
  4. Use a scan tool in order to monitor the HO2S voltage.
  5. Ensure the ignition is ON while the engine is OFF.

Is the HO2S voltage less than the specified value?

20 mV

Go to Step 8

Go to Step 7

6
  1. Connect the test lamp between the HO2S heater ignition 1 voltage circuit terminal at the engine harness side and a clean body ground.
  2. Ensure the ignition is ON, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 10

7
  1. Turn OFF the ignition.
  2. Remove the jumpers from the PCM connector containing the HO2S high signal and low signal circuits.
  3. Use a DMM in order to measure the continuity of the HO2S high signal circuit and then the HO2S low signal circuit between the PCM connector terminal and the HO2S connector terminal at the engine harness side.

Does the resistance measure less than the specified value?

5ohms

Go to Step 12

Go to Step 11

8

Replace the HO2S. Refer to Heated Oxygen Sensor Replacement .

Did you complete the replacement?

--

Go to Step 14

--

9

Repair the open HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

10
  1. Repair the lack of voltage on the HO2S heater ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.
  2. If the fuse is blown, repair the short to ground on the circuit. A blown fuse or lack of voltage to the fuse may cause other DTCs or symptoms to be present. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

11

Repair the circuit that measured high resistance. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

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12
  1. Check for proper PCM terminal contact.
  2. Repair the connectors as necessary. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

Go to Step 13

13

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 14

--

14
  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 15

15

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