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Home >> Chrysler >> 2002 >> Neon LE, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0134: 1/1 O2 Sensor Stays At Center & DTC P0140: 1/2 O2 Sensor Stays At Center >> Testing
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DTC P0134: 1/1 O2 Sensor Stays At Center & DTC P0140: 1/2 O2 Sensor Stays At Center: 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  8 .
  2. Turn the ignition off. Disconnect the O2 sensor harness connector. Turn the ignition on. Using a test light connected to battery voltage, probe the O2 sensor signal circuit in the O2 sensor harness connector. With the DRBIII(R), read the O2 sensor voltage. Is the voltage more than one volt? If yes, replace the O2 sensor. If no, go to next step.
  3. Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the O2 sensor ground circuit between the O2 sensor harness connector and the PCM harness connector. Is the resistance less than 5.0 ohms? If yes, go to next step. If no, repair the O2 sensor ground circuit for an open.
  4. Measure the resistance of the O2 sensor signal circuit between the O2 sensor harness connector and the PCM harness connector. Is the resistance less than 5.0 ohms? If yes, go to next step. If no, repair the O2 sensor signal for an open.
    5. 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.
  5. Reconnect O2 sensor harness connector and PCM harness connectors. Perform a voltage drop test by backprobing 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.
    6. 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.
  6. Turn the ignition off. Perform a voltage drop test by backprobing between the O2 sensor signal 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 signal circuit.
  7. There are no possible causes remaining, replace PCM.
    8. 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.
  8. 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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