P0621 OBD II Trouble Code Generator Lamp L Control Circuit Malfunction

How to easily diagnose, repair, and info on causes of a P0621 trouble code that indicates a detected failure of the generator lamp L control circuit.

Symptoms of P0621 OBD II Trouble Code

  • Engine drivability issues
  • Engine stall when idling
  • Inadvertent engine shutoff
  • Delayed engine cranking
  • Other stored codes

Common Causes of P0621 OBD II Trouble Code

  • Faulty PCM
  • PCM programming error
  • Open or shorted generator lamp control circuit
  • Defective alternator/generator
  • Failed generator lamp bulb

Severity of P0621 OBD II Trouble Code

Internal control module codes must always be taken seriously. A stored code P0621 could result in a variety of drivability concerns, including a no-start and/or dead battery condition.