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DTC P0135: 1/1 O2 Sensor Heater Failure: Testing

  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 step  3 . If no, go to next step.
    2. NOTE: Turn the ignition off and wait at least 8 minutes to allow O2 sensor to cool until O2 sensor voltage has stabilized to 0.4-0.6 volt.
  2. Turn the ignition on. With the DRBIII(R), actuate the O2 Heater Test. With the DRBIII(R), monitor O2 sensor voltage for at least 2 minutes. Does the voltage stay 0.4-0.6 volt? If yes, go to next step. If no, go to step  8 .
    3. NOTE: Allow the O2 sensor to cool down to room temperature.
  3. Turn the ignition off. Disconnect the O2 sensor harness connector. Measure the resistance across the O2 sensor heater element (component side). Is the resistance 2.0-7.0 ohms? If yes, go to next step. If no, replace O2 sensor.
  4. Disconnect the PCM harness connectors. Measure the resistance of the O2 sensor heater control 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 heater control circuit for an open.
  5. Measure the resistance between ground and the O2 sensor heater control circuit in the O2 sensor harness connector. Is the resistance less than 5.0 ohms? If yes, repair the O2 sensor heater control circuit for a short to ground. If no, go to next step.
  6. Turn the ignition off. Reconnect the PCM harness connectors. With the DRBIII(R), actuate the O2 Heater Test. Measure the voltage on the ASD relay output circuit in the O2 sensor harness connector. Is the voltage more than 11.0 volts? If yes, go to next step. If no, repair the ASD relay output circuit for an open.
  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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