LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Jeep >> 2023 >> Compass Red >> Repair and Diagnosis >> Engine Performance >> System >> 2.0L - DTCS P0117 To P018C >> DTC Troubleshooting >> P0141-O2 Sensor 1/2 Heater Performance >> Diagnostic Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Test

  1. CHECK FOR ANY SERVICE BULLETINS OR PCM SOFTWARE UPDATES 
    1. Check for any applicable Service Bulletins or Flash updates related to the DTC.

      Are there any applicable Service Bulletins or Flash updates?

      Yes 

      No 

      • Go To  2
  2. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. With the scan tool, run a vehicle Scan Report or record the Environmental Data related to the DTCs.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Turn the ignition on.
    6. Using the recorded Environmental Data and the When Monitored Conditions above, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  3

      No 

  3. CHECK THE O2 SENSOR 1/2 (K299) HEATER CONTROL CIRCUIT AND (Z909) GROUND CIRCUIT BY LOAD TESTING THE CIRCUITS 
    NOTE:

    Why load test a circuit?  A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered  and draws approximately 2.0 amps of current. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT TESTING PROCEDURES .

    NOTE:

    A 12-volt test light can be substituted for the load test tool, but only  if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps.

    1. Turn the ignition off.
    2. Disconnect the O2 Sensor 1/2 harness connector.
    3. Disconnect the PCM C2 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 the GPEC Diagnostic Adaptor to perform the diagnosis.

    4. If it is necessary to probe a terminal at a PCM harness connector, connect the (special tool #10436, Adapter, GPEC Diagnostic) to the appropriate PCM harness connector.
      NOTE:

      The GPEC Diagnostic Adaptor can add up to 1.5 Ohms of resistance to the circuit.

    5. Connect one lead of a load test tool to the O2 Sensor 1/2 (K299) Heater Control circuit and the other lead to the (Z909) Ground circuit at the O2 Sensor 1/2 harness connector.
    6. Load test the circuit by connecting a fused jumper between Battery (+) and the O2 Sensor 1/2 (K299) Heater Control circuit at the GPEC Adaptor.
      NOTE:

      Compare the brightness of the bulb in the load test tool to that of a direct connection to Battery.

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To  5

      No 

      • Go To  4
  4. DETERMINE IF THE OPEN OR HIGH RESISTANCE IS IN THE O2 SENSOR 1/2 (K299) HEATER CONTROL CIRCUIT BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the lead of the load test tool that is connected to the (Z909) Ground circuit at the O2 Sensor 1/2 harness connector.
    2. Connect the lead to a good chassis ground to determine if the open or high resistance is in the O2 Sensor 1/2 (K299) Heater Control circuit.

      Is the load test bulb illuminated and bright?

      Yes 

      • Repair the (Z909) Ground circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Repair the O2 Sensor 1/2 (K299) Heater Control circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  5. CHECK THE PCM HEATER CONTROL DRIVER FOR PROPER OPERATION 
    1. Reconnect the PCM C2 harness connector.
    2. Turn the ignition on.
    3. With the scan tool, actuate the Oxygen Sensor 1/2 control to the maximum allowable percentage.
    4. Using a 12-volt test light connected to ground, probe the O2 Sensor 1/2 (K299) Heater Control circuit in the Oxygen Sensor 1/2 harness connector.
      NOTE:

      The test light should be illuminated. The brightness will be dependant on the actuation percentage selected.

    5. With the scan tool, actuate the Oxygen Sensor 1/2 control to the OFF (0%) position.
    6. Using a 12-volt test light connected to ground, check the O2 Sensor 1/2 (K299) Heater Control circuit in the Oxygen Sensor 1/2 harness connector.
      NOTE:

      The test light should not be illuminated.

      Does the test light illuminate with the actuator ON and not illuminated with the actuator OFF?

      Yes 

      No 

      • Go To  6
  6. CHECK RELATED PCM AND COMPONENT CONNECTIONS 
    1. Perform any Service Bulletins that apply.
    2. Disconnect all PCM harness connectors.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    9. With the scan tool, erase DTCs.
    10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    11. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
scientia non olet · About LEMON Manuals