GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Tracker - 4WD 🢒 DTC 🢒 DTC P2232 or P2235

Circuit Description

The DTC P2231, P2232, P2234, or P2235 HO2S Signal Circuit Shorted to Heater Circuit Bank x Sensor x diagnostic monitors the signal circuit of the bank 1 or bank 2 fuel control or post catalyst oxygen sensor. The heated oxygen sensor (HO2S) contains a heating element that receives ignition voltage. If the heater ignition voltage circuit is shorted to the signal circuit, the voltage on the signal circuit will exceed 2.0 volts. If the signal circuit voltage remains excessively high for an extended period of time the respective DTC will set.

Conditions for Running the DTC
    • The barometric pressure (BARO) is more than 75 kPa.
    • The engine coolant temperature (ECT) is between -8°C and +110°C (18°F-230°F).
    • The intake air temperature (IAT) is more than -8°C (+18°F) at engine start up.
    • The vehicle speed is more than 56 km/h (35 mph) for 2 minutes and then idled for 1 minute.

Conditions for Setting the DTC

The HO2S voltage is more than 2,000 mV for a specified period of time.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC
    • The MIL turns OFF after 3 consecutively passing trips without a fault present.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • Perform the scan tool Clear DTC Information function in order to clear the DTC.

Diagnostic Aids

Check for any of the following conditions:

    • If any DTCs other than fuel trim P0171, P0172, P0174, P0175, misfire P0300 - P0306, exhaust gas recirculation (EGR) P0400, and other HO2S are set, diagnosis those DTCs first.
    • The DTC is more likely to set during city driving. Avoid operating the vehicle only on the highway when validating the DTC.
    • A shorted HO2S--If the HO2S is internally shorted to voltage, the HO2S reading displayed on the scan tool will be more than 1 volt. Water contamination of the HO2S can cause a high HO2S voltage to be indicated. If the DTC occurs when driving through standing water or when operating the vehicle in wet driving conditions, replace the HO2S if the sensor is adversely affected by moisture.

If the DTC is intermittent, driving the vehicle under the conditions outlined in the Inspection/Maintenance (I/M) section can verify whether the fault is present. Refer to Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor System Set .

An intermittent malfunction may be caused by a problem in the HO2S electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

If the DTC cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

Test Description

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

  1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

    2.

  2. This step determines if the fault is present. The vehicle must be at operating temperature.

    3.

  3. This step checks whether the malfunction that caused the DTC is still present. Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC appears in the Not Ran Since Code Cleared list, the DTC diagnostic has not yet run. When the DTC does not appear in the Not Ran Since Code Cleared list, the DTC diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.

    4.

  4. This step checks for an open in the HO2S ground circuit.

    5.

  5. This step checks for a short in the HO2S signal circuit.

    6.

  6. Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC appears in the Not Ran Since Code Cleared list, the DTC diagnostic has not yet run. When the DTC does not appear in the Not Ran Since Code Cleared list, the DTC diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.

Step

Action

Value(s)

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

  1. Start the engine.
  2. Run the engine until the engine reaches a normal operating temperature.
  3. Increase the engine speed to 2,000 RPM for 1 minute.
  4. Monitor the HO2S voltage with a scan tool.

Does the HO2S voltage switch below and above the specified value?

300-600 mV

Go to Step 3

Go to Step 4

3

  1. Turn ON the ignition, leaving the engine OFF.
  2. Perform the scan tool clear DTC information function.
  3. Start the engine.
  4. Operate the vehicle within Freeze Frame conditions as specified or until the DTC diagnostic test has run. Refer to the Test Description.

Does the HO2S voltage switch below and above the specified value?

300-600 mV

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the HO2S electrical connector.
  3. Turn ON the ignition, leaving the engine OFF.
  4. Probe the harness side of the HO2S ground circuit with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 6

5

  1. Turn OFF the ignition.
  2. Disconnect the C2 electrical connector of the PCM.
  3. Turn ON the ignition, leaving the engine OFF.
  4. Connect a DMM from ground to the oxygen sensor signal circuit on the harness side of the electrical connector.

Is the voltage at the specified value?

0.0 V

Go to Step 8

Go to Step 7

6
  1. Test for an open in the HO2S ground circuit.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

7
  1. Test the HO2S signal circuit for a short to voltage.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the HO2S. Refer to Heated Oxygen Sensor 1 Replacement or Heated Oxygen Sensor 2 Replacement .

Did you complete the replacement?

--

Go to Step 10

--

9

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Turn OFF the ignition.
  2. Remove the DOME fuse for 30 seconds.
  3. Install the DOME fuse.
  4. Reset the radio clock time. Refer to Radio/Audio System Description and Operation in Entertainment.
  5. Start the engine.
  6. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or until the DTC diagnostic test has run.

Does the DTC run and pass?

--

Go to Step 11

Go to Step 2

11

With a 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