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Home › Dodge and Ram › 2002 › Dakota R/T, 2D Pickup › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0136: 1/2 O2 Sensor Heater Circuit Malfunction › Testing

DTC P0136: 1/2 O2 Sensor Heater Circuit Malfunction: Testing

  1. Turn the ignition on, with the engine off. With the DRBIII®, read DTCs. Is the DTC Good Trip Counter displayed and equal to zero? If yes, go to next step. If no, go to step  7.
    2. NOTE: O2 sensor heater relay may also be referred to as O2 heater relay or O2 relay.
  2. Turn the ignition off. Remove the O2 heater relay from the Power Distribution Center (PDC). Turn the ignition on, with the engine off. With the DRBIII®, actuate the Automatic Shutdown (ASD) relay. Using a 12-volt test light connected to ground, probe both of the ASD output (feed) cavities at the O2 heater relay connector in the PDC. Does the test light illuminate brightly when the relay actuates? If yes, go to next step. If no, repair the heater relay supply circuit for an open or short to ground. Turn the ignition off. Check the related fuse.
  3. Disconnect the PCM harness connectors. Measure the resistance of the O2 sensor heater relay control circuit between the O2 heater relay connector in the PDC and the PCM harness connector. Is the resistance less than 5.0 ohms? If yes, go to next step. If no, repair the open O2 sensor heater relay control circuit.
  4. Measure the resistance between ground and the O2 sensor heater relay control circuit in the O2 sensor heater relay connector in the PDC. Is the resistance less than 100 ohms? If yes, repair the short to ground in the O2 sensor heater relay control circuit. If no, go to next step.
  5. Measure the resistance of the O2 sensor relay coil (component side). Is the resistance more 100 ohms? If yes, replace the O2 relay. If no, go to next step.
  6. There are no possible causes remaining, replace the PCM.
    7. 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.
  7. Conditions that set DTC are not present at this time. The following list may help in identifying the intermittent condition:
    • Check for contaminants that may have damaged the O2 sensor, such as contaminated fuel, unapproved silicone, oil and coolant.
    • With the engine running at normal operating temperature, monitor the DRBIII® 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® Freeze Frame information. Attempt to duplicate condition that caused DTC to 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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