All fault codes

P0650: OBD-II code P0650 flags a fault in the MIL (check engine light) control circuit — the PCM can't reliably illuminate the CEL when needed.

LowPowertrainEngine/Powertrain

Symptoms

  • The check engine light may fail to illuminate when it should, or stay illuminated when it shouldn't.
  • The bulb-check function at ignition-on may not work correctly.
  • No drivability symptoms — but the fault hides other stored codes that would normally light the CEL for the driver.

Common causes

  • A burnt-out MIL bulb (on older vehicles with incandescent lamps).
  • Damaged wiring or a corroded connector on the MIL control line between the PCM and the instrument cluster.
  • A failed PCM MIL driver circuit — less common but possible.

What to do?

Check the MIL bulb (if applicable) and replace if burnt out. Verify wiring between the PCM and the instrument cluster. If the bulb and wiring test good, the PCM driver has failed and the module needs replacement or repair.