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Home >> Chrysler >> 2021 >> Voyager LX, Gas >> Repair and Diagnosis >> Engine Performance >> System >> 3.6L - DTCS P1057 To P1D73 >> Diagnosis And Testing >> P1621-O2 Sensor Reference Voltage Circuit Low >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR ANY APPLICABLE SERVICE BULLETINS 
    1. Check for any Service Bulletins or flash updates that may apply.

      Are there any Service Bulletins or flash updates available?

      Yes 

      No 

      • Go To  2
  2. CHECK FOR AN ACTIVE DTC 
    1. Start the engine and allow it to idle long enough for the O2 Sensors to enter closed loop operation (approximately 30 seconds).
    2. With the scan tool, read DTCs and record on the repair order.

      Is the DTC active or pending?

      Yes 

      • Go To  3

      No 

  3. CHECK THE O2 SENSOR VOLTAGE READINGS WITH THE SCAN TOOL 
    1. With the scan tool select the Data tab and monitor all of the O2 Sensor voltage readings.
      NOTE:

      Check the voltage readings for all of the O2 Sensors to determine if all of the sensors are switching between 0-1 volt or if any one sensor is stuck near 0.0 volts.

      Pick the correct scenario below:

      All O2 Sensors are switching between 0-1 volts on the biased O2 Sensor Signal voltage reading: 

      • Go To  4

      One O2 Sensor is reading 0.0 volts and the other O2 Sensors are switching between 0-1 volts on the biased O2 Sensor Signal voltage reading: 

      • This indicates a short to ground on the signal circuit of the sensor reading near 0.0 volts. Repair the O2 Sensor Signal circuit of the O2 Sensor that is reading near 0.0 volts for a short to ground. If it is determined that the signal circuit is not shorted to ground, the O2 Sensor is likely internally shorted.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECK FOR A SHORTED O2 SENSOR 
    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.

    1. Disconnect any one of the O2 Sensor harness connectors.
    2. With the scan tool, monitor the voltage readings of the O2 Sensors that are STILL CONNECTED.
      NOTE:

      If the fault is caused by an O2 Sensor that is internally shorted, the other O2 Sensors should change from switching between 0-1 volts to switching between 2.5 - 3.5 volts when the faulty O2 Sensor is disconnected.

    3. Reconnect the O2 Sensor harness connector and repeat this step for each of the O2 Sensors on the vehicle.

      Did the voltages change to approximately 2.5 - 3.5 volts for the O2 Sensors STILL CONNECTED when disconnecting any one of the sensors?

      Yes 

      No 

      • Go To  5
  5. CHECK THE (K902) O2 SENSOR UPSTREAM RETURN CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Disconnect the PCM C2 harness connector.
    3. Disconnect the O2 Sensor 1/1 harness connector.
    4. Disconnect the O2 Sensor 2/1 harness connector.
    5. Check for continuity between ground and the (K902) O2 Sensor Upstream Return circuit at the O2 Sensor 1/1 or 2/1 harness connector.

      Is there continuity between ground and the (K902) O2 Sensor Upstream Return circuit?

      Yes 

      • Repair the (K902) O2 Sensor Upstream Return circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  6
  6. CHECK THE (K904) O2 SENSOR DOWNSTREAM RETURN CIRCUIT FOR A SHORT TO GROUND 
    1. Disconnect the O2 Sensor 1/2 harness connector.
    2. Disconnect the O2 Sensor 2/2 harness connector.
    3. Check for continuity between ground and the (K904) O2 Sensor Downstream Return circuit at the O2 Sensor 1/2 or 2/2 harness connector.

      Is there continuity between ground and the (K904) O2 Sensor Downstream Return circuit?

      Yes 

      • Repair the (K904) O2 Sensor Downstream Return circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  7
  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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