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Home >> Jeep >> 2024 >> Wagoneer Carbide, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (3.0L - DTCS P0160-00 To P0192-00) >> DTC Troubleshooting >> P0161-00-02 Sensor Heater 2/2 Resistance >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2024 Jeep Grand Wagoneer L and 2024 Jeep Grand Wagoneer. However, it is still accessible from the selected car via links, so may be relevant.
  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. PERFORM THE O2 SENSOR 2/2 HEATER OPERATION TEST USING THE SCAN TOOL TO CHECK FOR AN ACTIVE CONDITION 
    1. Turn the ignition off.
      NOTE:

      Wait a minimum of eight minutes to allow the sensor to cool down before continuing. The sensor voltage should stabilize between 2.47 and 2.52 volts.

    2. Turn the ignition on.
    3. With a scan tool, actuate the Oxygen Sensor 2/2 heater control.
    4. With the scan tool, monitor the O2 Sensor 2/2 voltage for at least two minutes.

      Does the voltage stay above approximately 4.5 volts?

      Yes 

      • Go To  3

      No 

  3. CHECK FOR OTHER DTCS 
    1. Refer to the recorded DTCs.

      Are there any O2 Sensor Heater circuit DTCs present?

      Yes 

      No 

      • Go To  4
  4. CHECK THE O2 SENSOR 2/2 HEATER ELEMENT RESISTANCE 
    1. Turn the ignition off.
      NOTE:

      Allow the O2 Sensor heater to cool down from the heater test performed with the scan tool.

    2. Disconnect the O2 Sensor 2/2 harness connector.
    3. Measure the resistance of the O2 Sensor 2/2 Heater Element across the O2 Sensor, between the O2 Heater Control terminal and the Heater ground terminal (component side).
      NOTE:

      If possible, it's best to measure the O2 Sensor 2/2 Heater Element resistance value at approximately 20°C (68°F). The resistance value will vary with different temperature values. If the O2 Sensor is obviously warmer or cooler than the recommended temperature, use the table below to estimate what the resistance range should be. The MAXIMUM allowable resistance would be 12.5 Ohms at 1000°C.

      Celsius Fahrenheit Resistance Range
      0°C 32°F 3.1 - 4.2 Ohms
      20°C 68°F 3.3 - 4.4 Ohms
      100°C 212°F 3.85 - 5.1 Ohms

      Is the O2 Sensor resistance within the acceptable range?

      Yes 

      • Go To  5

      No 

      • Verify that there is good pin to terminal contact in the O2 Sensor and PCM harness connectors. If no problems are found, replace the O2 Sensor in accordance with the Service Information. Refer to OXYGEN SENSOR(S) .
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  5. CHECK THE (K908) RETURN CIRCUIT FOR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the component harness connector to isolate the return circuit.
    2. Connect the positive lead of the load test tool to the positive side of the Battery.
    3. Connect the negative lead of the load test tool to the return circuit at the component harness connector (A). Note:  refer to the diagram below.
    4. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuitry.
      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. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. 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 LOAD 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.

      NOTE:

      Why perform a Voltage Drop Test?  To verify with certainty there is not any resistance in the circuit being tested, perform a simple voltage drop test across the 3156 bulb of the load test tool. To do so perform the following:

      • 1. Connect the leads of a DVOM to the alligator clips on the load test tool while the load test tool is connected in series with the circuit.
      • 2. Compare the voltage drop across the bulb to the voltage reading across the Battery terminals.
      • 3. The voltage dropped across the bulb should be equal to the voltage reading across the Battery terminals if there is no resistance in the circuit being tested.

      Example:  2.0 Ohms of resistance in the circuit being tested will cause the voltage measurement across the bulb to be 25% less than when compared to Battery voltage. The reason for this is that the 2.0 Ohms in the circuit makes up 25% of the total circuit resistance of 8.0 Ohms. 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 LOAD TESTING PROCEDURES .

      NOTE:

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

      GC0174957Courtesy of CHRYSLER GROUP, LLC

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To  6

      No 

      • Repair the return circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. ISOLATE AND LOAD TEST THE O2 SENSOR 2/2 (K399) HEATER CONTROL CIRCUIT TO CHECK FOR HIGH RESISTANCE 
    1. The ignition must be off when performing a load test on a circuit.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested.
    3. Connect the positive lead of the load test tool to the positive side of the Battery (A). Note:  Refer to the diagram below.
    4. Using an approved back probe tool, connect the negative lead of the load test tool to the circuit being tested at the one of the component harness connectors (B).
    5. Using an approved back probe tool and a fused jumper wire, connect the circuit being tested to the negative side of the Battery or a known good return at the other component harness connector (C and D).
    6. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuit.
      NOTE:

      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. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. 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 LOAD TESTING PROCEDURES .

      NOTE:

      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.

      NOTE:

      Note: Why perform a Voltage Drop Test?  To verify with certainty there is not any resistance in the circuit being tested, perform a simple voltage drop test across the 3156 bulb of the load test tool. To do so perform the following:

      • 1. Connect the leads of a DVOM to the alligator clips on the load test tool while the load test tool is connected in series with the circuit.
      • 2. Compare the voltage drop across the bulb to the voltage reading across the Battery terminals.
      • 3. The voltage dropped across the bulb should be equal to the voltage reading across the Battery terminals if there is no resistance in the circuit being tested.

      Example:  2.0 Ohms of resistance in the circuit being tested will cause the voltage measurement across the bulb to be 25% less than when compared to Battery voltage. The reason for this is that the 2.0 Ohms in the circuit makes up 25% of the total circuit resistance of 8.0 Ohms. 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 LOAD TESTING PROCEDURES .

      WARNING:

      To avoid possible serious or fatal injury, DO NOT load test any air bag/restraint system components or circuits using the procedures listed here. Refer to the Service Information for proper air bag/restraint system testing procedures.

      CAUTION:

      Do not load test any circuits with components still connected to the circuit.

      NOTE:

      There should be no continuity between return and the circuit being tested.

      NOTE:

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

      GC0174954Courtesy of CHRYSLER GROUP, LLC

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To  7

      No 

  7. 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 .
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