121.01CS421dn
Lexmark CS421dn 121.01 Error: Fix and Troubleshooting
The Lexmark CS421dn 121.01 error signifies a malfunction in the primary input tray sensor. This fault prevents printing by incorrectly reporting the paper status, often following a jam. To fix the Lexmark CS421dn 121.01 error, inspect the paper path for obstructions and perform a power reset.
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Common causes
- 1Debris blocking the sensor lens.
- 2Tray improperly seated.
- 3Sensor actuator fatigue.
- 4Loose cabling connection to the tray assembly.
Solutions
Diagnóstico rápido
This error appears on the display when the printer cannot confirm paper presence. Checking if the tray is properly seated is the first step in understanding why does my Lexmark CS421dn show 121.01 error.Solución paso a paso
- Turn off the printer and unplug it.
- Remove the input tray entirely.
- Clean the sensor path with compressed air or a lint-free cloth.
- Reinsert the tray and restart the machine.
Prevención y mantenimiento
Keep the printer in a clean environment and wipe the pickup rollers with a damp cloth periodically. Using genuine supplies helps keep the internal mechanisms clean.Cuándo llamar a un técnico
If the error persists after cleaning, the physical sensor may be faulty or broken.Ficha técnica del equipo
- Technology: Color Laser
- Speed: 40 ppm
- Connectivity: Ethernet/USB
- Compatible Consumables: CS421 Series (78C20)
- Official Drivers / firmware
Steps to follow
- 1
Remove tray
Pull out the paper tray completely from the printer.
- 2
Inspect sensors
Check for paper scraps blocking the sensor area.
- 3
Reboot
Power cycle the device to reset sensor readings.
Frequently asked questions
This occurs when the tray sensor fails to detect paper, usually due to debris or misalignment.
No, it is usually a simple mechanical obstruction that is easy to fix.
It uses the Lexmark CS421 toner cartridge series.
Cleaning every 50,000 pages is recommended to maintain performance.