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Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
    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 When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

  2. CHECK FOR ANY SERVICE BULLETINS OR PCM SOFTWARE UPDATES 
    NOTE:

    Any O2 Sensor heater or signal circuit DTCs should be diagnosed before continuing with this procedure.

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

      Are there any O2 Sensor heater or signal circuit DTCs present?

      Yes 

      • Perform the applicable diagnostic procedure(s). Refer to DTC INDEX .

      No 

      • Go To  4
  4. CHECK THE INTAKE SYSTEM AND AIR FILTER FOR RESTRICTIONS OR BLOCKAGE 
    1. Check for a blockage in the intake air system plumbing.
    2. Visually inspect the Air Filter for a restriction.
      NOTE:

      Poor airflow due to a severely restricted Air Filter can cause this DTC to set.

      Were any issues found?

      Yes 

      No 

      • Go To  5
  5. CHECK THE O2 SENSOR FOR PROPER MOUNTING 
    1. Check and verify that the Upstream O2 Sensor is mounted correctly into the exhaust. Verify the sensor is tight and not cross threaded.

      Is the O2 Sensor mounted correctly?

      Yes 

      • Go To  6

      No 

  6. CHECK THE ORIENTATION OF THE UPSTREAM AND DOWNSTREAM O2 SENSOR HARNESS CONNECTORS 
    1. Check and verify that the Upstream O2 Sensor and Downstream O2 Sensor harness connectors are properly connected to the correct sensors.

      Are the harness connectors reversed?

      Yes 

      No 

      • Go To  7
  7. CHECK THE EXHAUST SYSTEM FOR LEAKS 
    1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure. Refer to CHECKING THE EXHAUST SYSTEM FOR LEAKS .

      Were any exhaust leaks found?

      Yes 

      • Repair or replace the leaking exhaust parts as necessary.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  8
  8. REPLACE THE O2 SENSOR 1/2 AND RETEST FOR DTC 
    NOTE:

    Check for signs of contaminants that may have damaged the O2 Sensor, such as contaminated fuel, unapproved silicone, oil and coolant.

    1. Replace the O2 Sensor 1/2 in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL AND INSTALLATION .
    2. Connect the O2 Sensor 1/2 and PCM harness connectors.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Using the recorded Freeze Frame and the When Monitored conditions, operate the vehicle in the conditions that set the DTC.
    6. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  9

      No 

      • Replacing the O2 Sensor 1/2 repaired the fault. If the O2 Sensor was contaminated, also correct the engine mechanical condition that caused the contamination on the sensor.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  9. 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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