LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chrysler >> 2010 >> PT Cruiser >> Repair and Diagnosis >> Engine Performance >> System >> Gas - DTCS P0135 To P0440 >> P0138-O2 Sensor 1/2 Circuit High >> Diagnostic Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Test

  1. O2 SENSOR ABOVE 3.7 VOLTS 
    NOTE: When only one O2 Sensor is shorted to voltage, the scan tool will display all O2 Sensor voltage readings at approximately 5.0 volts. When diagnosing this DTC, only diagnose the O2 Sensor that set the DTC.
    1. Start the engine.
    2. Allow the engine to reach normal operating temperature.
    3. With a scan tool, read the 1/2 O2 Sensor voltage.

      Is the voltage above 3.7 volts?

      Yes 

      • Go to step  2

      No 

  2. (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE 
    Fig 1: Measuring Voltage On O2 Sensor 1/2 Signal Circuit
    GC0117198Courtesy of CHRYSLER LLC
    1. Start the engine and allow the engine to idle.
    2. Disconnect the 1/2 O2 Sensor harness connector.
    3. Measure the voltage on the (K141) O2 Sensor 1/2 Signal circuit in the O2 Sensor harness connector.
      NOTE: Measure the voltage in reference to ground, not the (K902) O2 Downstream Return circuit.

      Is the voltage above 5.2 volts?

      Yes 

      • Repair the short to battery voltage in the (K141) O2 Sensor 1/2 Signal circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. See POWERTRAIN VERIFICATION TEST .

      No 

      • Go to step  3
  3. (K902) O2 DOWNSTREAM RETURN CIRCUIT SHORTED TO BATTERY VOLTAGE 
    Fig 2: Measuring Voltage On O2 Sensor Return Circuit
    GC0117194Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the PCM harness connectors.
    3. Ignition on, engine not running.
    4. Measure the voltage on the (K902) O2 Downstream Return circuit in the O2 Sensor harness connector.

      Is there any voltage present?

      Yes 

      • Repair the short to battery voltage in the (K902) O2 Downstream Return circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. See POWERTRAIN VERIFICATION TEST .

      No 

      • Go to step  4
  4. O2 SENSOR 
    Fig 3: Checking O2 Sensor 1/2 Signal Circuit
    GC0117199Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Connect the PCM harness connectors.
    3. Connect a jumper wire between the (K141) O2 1/2 Signal circuit and the (K902) O2 Downstream Return circuit in the 1/2 O2 Sensor harness connector.
    4. Ignition on, engine not running.
    5. With a scan tool, monitor the 1/2 O2 Sensor voltage.

      Is the voltage between 2.3 and 2.7 volts with the jumper wire installed?

      Yes 

      No 

      • Go to step  5
        NOTE: Remove the jumper wire before continuing.
  5. (K141) O2 1/2 SIGNAL CIRCUIT OPEN 
    Fig 4: Checking O2 1/2 Signal Circuit For An Open
    GC0117200Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
      CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install PCM Pinout Box 8815 to perform diagnosis.
    2. Measure the resistance of the (K141) O2 1/2 Signal circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.

      Is the resistance below 5.0 ohms?

      Yes 

      • Go to step  6

      No 

  6. (K902) O2 DOWNSTREAM RETURN CIRCUIT OPEN 
    Fig 5: Checking O2 Downstream Return Circuit
    GC0117201Courtesy of CHRYSLER LLC
    1. Measure the resistance of the (K902) O2 Downstream Return circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.

      Is the resistance below 5.0 ohms?

      Yes 

      • Go to step  7

      No 

  7. PCM 
    NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
    1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

      Were there any problems found?

      Yes 

      No 

      • Replace and program the Powertrain Control Module per Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. See POWERTRAIN VERIFICATION TEST .