HP Laserjet Error Codes 13 21 DOOR OPEN JAM

1. Check the transfer roller a

nd small media belt to ensure they are operating and can feed print media.
2. Check the paper path for obstructions at the transfer roller, toner cartridge, paper feed assembly, and fuser.
3. Replace any defective sensors or flags.
4. Turn the media stack over and/ or rotate it by 180° in the input tray.