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Home >> Jeep >> 2021 >> Cherokee High Altitude, Full Time T/Case Control >> Repair and Diagnosis >> Engine Performance >> System >> 2.0L - DTCS P2173 To U0299 >> DTC Troubleshooting >> P2271-O2 Sensor 1/2 Signal Biased Rich >> Diagnostic Test
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Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. Start the engine and allow it to reach operating temperature.
      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 may result in possible serious or fatal injury.

      NOTE:

      It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.

    2. With the scan tool, read the active DTCs.

      Is the DTC active?

      Yes 

      • Go To  2

      No 

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

      Are there any Fuel or Ignition system DTCs present?

      Yes 

      No 

      • Go To  3
  3. REPLACE THE DOWNSTREAM O2 SENSOR 1/2 AND RETEST FOR DTC 
    1. Verify that there is good pin to terminal contact in the O2 Sensor 1/2 and Powertrain Control Module connectors. Replace the O2 Sensor 1/2 in accordance with the Service Information. Refer to REMOVAL .
    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  4

      No 

  4. 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 .