Ford P0621 OBD-II Trouble Code Definition: P0621 Generator Lamp L Control Circuit Malfunction P0621 Ford OBD-II Trouble CodeDescription: OBD Trouble Code P0621 Generator Lamp/L Terminal Circuit What does the code mean? OBD-ii Code P0621 definition: The Engine Control Module (ECM) or Powertrain Control Module (PCM) uses the generator turn on signal circuit to control the load […]