2002 Chrysler Neon LE, AutomaticFACTORY OEM SERVICE PROCEDURE

DTC P0133: 1/1 O2 Sensor Slow Response & DTC P0139: 1/2 O2 Sensor Slow Response: Testing

NOTE: Before proceeding, check for contaminants that may have damaged O2 sensor such as contaminated fuel, unapproved silicone, oil and coolant.
  1. Turn the ignition on. With the DRBIII(R), read DTCs. Is the Good Trip counter displayed and equal to zero? If yes, go to next step. If no, go to step  6 .
  2. Start the engine. Allow the engine to idle. Inspect the exhaust system for leaks between the engine and the O2 sensors. Are there any exhaust leaks? If yes, repair or replace the leaking exhaust parts as necessary. If no, go to next step.
    3. NOTE: Ensure the voltmeter leads meet the terminals in the connector and that there is good terminal-to-wire connection. Ensure the voltmeter leads are connected for positive polarity.
  3. Turn the ignition off. Perform a voltage drop test by backprobing the O2 sensor signal circuit in the O2 sensor harness connector and the PCM harness connector. Start the engine. Allow the engine to idle. Is the voltage less than 0.10 volt? If yes, go to next step. If no, repair the high resistance on the O2 sensor signal circuit.
    4. NOTE: Ensure the voltmeter leads meet the terminals in the connector and that there is good terminal-to-wire connection. Ensure the voltmeter leads are connected for positive polarity.
  4. Turn the ignition off. Backprobe between the O2 sensor ground circuit in the O2 sensor harness connector and PCM harness connector. Start the engine. Allow the engine to idle. Is the voltage less than 0.10 volt? If yes, go to next step. If no, repair the high resistance on the O2 sensor ground circuit.
  5. There are no possible causes remaining, replace PCM.
    6. WARNING: When the engine is operating, DO NOT stand in a direct line with the fan. DO NOT put your hands near the pulleys, belts or fan. DO NOT wear loose clothing.
  6. Conditions that set DTC are not present at this time. The following list may help in identifying the intermittent condition:
    • With the engine running at normal operating temperature, monitor the DRBIII(R) parameters related to the DTC while wiggling the wiring harness. Look for parameter values to change and/or a DTC to set.
    • Review the DRBIII(R) Freeze Frame information to identify under what conditions the DTC set.
    • Refer to any Technical Service Bulletin (TSB) that may apply.
    • Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires.
    • Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.

    Were any of the above conditions present? If yes, repair as necessary. If no, test is complete.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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