Lexus P1139: Lexus OBD-II Error Code P1139

Symptoms

The ECM has detected a manufacturer-specific ignition system or misfire fault. The check engine light may flash during misfire. DTC P1139 is stored in the Lexus engine control module.

Possible Causes

Spark plug worn or fouled
Ignition coil failure
Spark plug gap incorrect
Ignition control circuit fault

Troubleshooting Steps

Step 1: Connect an OBD-II scanner and read DTCs to confirm P1139
DTC P1139 present with freeze frame data
Step 2: Inspect wiring and connectors in the affected circuit for damage, corrosion, or loose pins
Wiring intact, connectors clean and seated
Step 3: Perform component-level testing per manufacturer service manual
Component values within spec or component confirmed faulty
Step 4: Repair or replace the faulty component, clear DTC, and verify no return
DTC cleared and does not return after a road test

How to Reset

Clear the DTC after repair using a diagnostic scanner. The code clears automatically if the fault is not detected for 3 consecutive drive cycles.

Common Replacement Parts

varies: Diagnose and replace the confirmed faulty component (Confirm part number via VIN at a Lexus dealership)

Frequently Asked Questions

Q: What does P1139 mean?
This manufacturer-specific DTC indicates a ignition system / misfire system fault. Refer to the vehicle's service manual for the exact diagnostic procedure.
Q: Can I drive with P1139?
Limited driving is possible, but the affected system may not operate correctly. Have the vehicle diagnosed promptly to prevent potential damage.

Lexus OBD-II Error Code P1139