LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chrysler >> 2007 >> 300 Base >> Repair and Diagnosis >> Engine Performance >> System >> DTCS P0125 To P0175 >> P0138-O2 Sensor 1/2 Circuit High >> Diagnostic Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Test

  1. 1) DTC IS ACTIVE 
    NOTE: If an O2 sensor signal circuit is shorted to voltage, all O2 sensor voltage readings displayed on the scan tool will be approximately 5.0 volts. Diagnose the sensor that set the most current DTC.

    Start the engine and allow it to idle for at least 60 seconds.

    WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

    With a scan tool, select View DTCs.

    Is the status Active for this DTC? 

    Yes 

    1. Go to  2).

    No 

    1. Refer to *CHECKING FOR AN INTERMITTENT DTC .
  2. 2) (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO VOLTAGE 
    Fig 1: Checking O2 Sensor Circuit
    GC0049470Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the 1/2 Oxygen Sensor harness connector.

    Disconnect the Powertrain Control Module (PCM) harness connector.

    Turn the ignition on.

    Measure the voltage of the (K141) O2 1/2 Signal circuit in the 1/2 Oxygen Sensor harness connector.

    NOTE: Measure the voltage in reference to ground, not the (K904) O2 Return (Down) circuit.

    Is there any voltage present? 

    Yes 

    1. Repair the (K141) O2 1/2 Signal circuit for a short to voltage.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to  3).
  3. 3) (K904) O2 RETURN (DOWN) CIRCUIT SHORTED TO VOLTAGE 
    Fig 2: Checking O2 Sensor Circuit
    GC0049466Courtesy of CHRYSLER LLC

    Measure the voltage on the (K904) O2 Return (Down) circuit in the 1/2 Oxygen Sensor harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the (K904) O2 Return (Down) circuit for a short to voltage.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to  4).
  4. 4) (K141) O2 1/2 SIGNAL CIRCUIT SHORTED TO THE (K299) O2 1/2 HEATER CONTROL CIRCUIT 
    Fig 3: Checking O2 Sensor Circuit
    GC0049479Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Measure the resistance between the (K141) O2 1/2 Signal circuit and the (K299) O2 1/2 Heater Control circuit the 1/2 Oxygen Sensor harness connector.

    Is the resistance below 100.0 ohms? 

    Yes 

    1. Repair the (K141) O2 1/2 Signal circuit for a short to the (K299) O2 1/2 Heater Control circuit.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to  5).
  5. 5) 1/2 OXYGEN SENSOR 

    Turn the ignition off.

    Connect the Powertrain Control Module (PCM) harness connector.

    Connect a jumper wire between the (K141) O2 1/2 Signal circuit and the (K904) O2 Return (Down) circuit in the 1/2 Oxygen Sensor harness connector.

    Turn the ignition on.

    With a scan tool, monitor the 1/2 Oxygen Sensor voltage.

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

    Yes 

    1. Replace the 1/2 Oxygen Sensor in accordance with the Service Information.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to  6).
  6. 6) (K141) O2 1/2 SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 4: Checking O2 Sensor Circuit
    GC0049475Courtesy of CHRYSLER LLC

    Turn the ignition off.

    If necessary, remove the jumper wire from between the (K141) O2 1/2 Signal circuit and the (K904) O2 Return (Down) circuit in the 1/2 Oxygen Sensor harness connector.

    Disconnect the Powertrain Control Module (PCM) harness connector.

    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 Miller Special Tool #8815 to perform diagnosis.

    Measure the resistance of the (K141) O2 1/2 Signal circuit between the 1/2 Oxygen Sensor harness connector and the appropriate terminal of special tool #8815.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Go to  7).

    No 

    1. Repair the (K141) O2 1/2 Signal circuit for an open circuit or high resistance.
    2. Perform *PCM VERIFICATION TEST .
  7. 7) (K904) O2 RETURN (DOWN) CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 5: Checking O2 Sensor Circuit
    GC0049476Courtesy of CHRYSLER LLC
    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 Miller Special Tool #8815 to perform diagnosis.

    Measure the resistance of the (K904) O2 Return (Down) circuit between the 1/2 Oxygen Sensor harness connector and the appropriate terminal of special tool #8815.

    Is the resistance below 5.0 ohms? 

    Yes 

    1. Go to  8).

    No 

    1. Repair the (K904) O2 Return (Down) circuit for an open circuit or high resistance.
    2. Perform *PCM VERIFICATION TEST .
  8. 8) POWERTRAIN CONTROL MODULE (PCM) 

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the 1/2 Oxygen Sensor and the Powertrain Control Module (PCM).

    Look for any chafed, pierced, pinched, or partially broken wires.

    Look for broken, bent, pushed out or corroded terminals.

    Refer to any Technical Service Bulletins that may apply.

    Were any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
    2. Perform *PCM VERIFICATION TEST .
scientia non olet · About LEMON Manuals