LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Jeep >> 2003 >> Wrangler Rubicon, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0136: 1/2 O2 Sensor Heater Circuit Malfunction >> Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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

  1. Turn ignition on, engine not running. 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 INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn the ignition off. Remove the Heater Relay from the PDC. Measurement is taken at the Heater Relay component. Measure the resistance of the O2 Sensor Heater Relay Coil. Is the resistance above 100 ohms? If yes, replace the O2 Sensor Heater Relay. If no, go to the next step.
  3. Turn ignition on, engine not running. With the DRBIII®, actuate the ASD Relay. Using a 12-volt test light connected to ground, probe the (F142) Fused ASD output voltage terminal of the O2 Heater Relay pin in the PDC. Does the test light illuminate brightly? If yes, go to next step. If no, repair the Heater Relay Supply circuit for an open and/or short to ground. Also check fuse No. 16 (15-amp) in the PDC.
  4. Turn the ignition off and disconnect the PCM harness connectors. Measure the resistance of the (K512) O2 Heater Relay Control circuit from the PDC (Heater Relay) connector to the PCM harness connector. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the (K512) O2 Sensor Heater Relay Control circuit.
  5. Measure the resistance between ground and the (K512) O2 Heater Relay Control circuit at the PDC connector. Is the resistance below 100 ohms? If yes, repair the short to ground in the (K512) O2 Sensor Heater Relay Control circuit. If no, go to next step.
    6. NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
  6. Using the wiring diagram as a guide, inspect the wire harness and connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
scientia non olet · About LEMON Manuals