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Home › Jeep › 2011 › Wrangler Sahara, Automatic › Repair and Diagnosis › Engine Performance › System › 3.8L - DTCS P0016 To P0204 › Diagnosis And Testing › P0157-O2 Sensor 2/2 Circuit Low › Diagnostic Test

Diagnostic Test

  1. ACTIVE DTC 
    1. Turn the ignition on.
    2. With a scan tool, select View DTCs. Record DTC and Freeze Frame information.
    3. 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 may result in possible serious or fatal injury.

    4. With a scan tool, select View DTCs.

      Is the DTC Active at this time?

      Yes 

      • Go To  2.

      No 

      • Refer to STANDARD PROCEDURE and perform the INTERMITTENT CONDITION Diagnostic Procedure.
  2. (K243) O2 2/2 SIGNAL CIRCUIT 
    1. Turn the ignition off.
    2. Disconnect the 2/2 O2 Sensor harness connector.
    3. Ignition on, engine not running.
    4. With a scan tool, monitor the 2/2 O2 Sensor voltage.

      Is the O2 Sensor voltage between 4.1 and 5.0 volts?

      Yes 

      • Go To  3.

      No 

      • Go To  5.
  3. O2 SENSOR 
    Fig 1: Measuring Voltage On O2 Sensor Return Circuit In O2 Sensor Harness Connector
    GC0090685Courtesy of CHRYSLER GROUP, LLC
    1. Measure the voltage on the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.

      Is the voltage at 2.5 volts?

      Yes 

      • Verify that there is good pin to terminal contact in the Oxygen Sensor and Powertrain Control Module connectors. If OK, replace the O2 Sensor.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.

      No 

      • Go To  4.
  4. (K904) O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO GROUND 
    Fig 2: Checking O2 Sensor Return Circuit For Short To Ground
    GC0090686Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off.
    2. Disconnect the C1 and C2 PCM harness connectors.
    3. Measure the resistance between ground and the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.

      Is the resistance below 100 ohms?

      Yes 

      • Repair the short to ground in the (K904) O2 Return Downstream circuit.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.

      No 

      • Go To  8.
  5. (K243) O2 2/2 SIGNAL CIRCUIT SHORTED TO GROUND 
    Fig 3: Checking O2 Sensor Signal Circuit For Short To Ground
    GC0090687Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off.
    2. Disconnect the C1 and C2 PCM harness connectors.
    3. Measure the resistance between ground and the (K243) O2 2/2 Signal circuit in the O2 Sensor harness connector.

      Is the resistance below 100 ohms?

      Yes 

      • Repair the short to ground in the (K243) O2 2/2 Signal circuit.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.

      No 

      • Go To  6.
  6. (K243) O2 2/2 SIGNAL CIRCUIT SHORTED TO THE (K904) O2 RETURN DOWNSTREAM CIRCUIT 
    Fig 4: Checking O2 Sensor Signal Circuit For Short To O2 Return Circuit
    GC0090688Courtesy of CHRYSLER GROUP, LLC
    1. Measure the resistance between the (K243) O2 2/2 Signal circuit and the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.

      Is the resistance below 100 ohms?

      Yes 

      • Repair the short between the (K904) O2 Return Downstream circuit and the (K243) O2 2/2 Signal circuit.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.

      No 

      • Go To  7.
  7. (K243) O2 2/2 SIGNAL CIRCUIT SHORTED TO THE (Z906) O2 2/2 HEATER GROUND CIRCUIT 
    Fig 5: Checking O2 Sensor Signal Circuit For Short To O2 Sensor Heater Ground Circuit
    GC0090689Courtesy of CHRYSLER GROUP, LLC
    1. Measure the resistance between the (K243) O2 2/2 Signal circuit and the (Z906) O2 2/2 Heater ground circuit in the O2 Sensor harness connector.

      Is the resistance below 100 ohms?

      Yes 

      • Repair the short between the (Z906) O2 2/2 Heater ground circuit and the (K243) O2 2/2 Signal circuit.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.

      No 

      • Go To  8.
  8. POWERTRAIN CONTROL MODULE (PCM) 
    1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen Sensor 2/2 and the Powertrain Control Module (PCM).
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Oxygen Sensor and Powertrain Control Module connectors.
    4. Refer to any Technical Service Bulletins that may apply.

      Were there any problems found?

      Yes 

      • Repair as necessary.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.

      No 

      • Replace and program the Powertrain Control Module per Service Information.
      • Refer to STANDARD PROCEDURE and perform the POWERTRAIN VERIFICATION TEST.
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