390B721n

OKI B721n Error 390: Troubleshooting and Solutions

The OKI B721n error 390 is a standard notification alerting to an issue within the device's paper transport system. This code typically surfaces when the internal sensors fail to register paper input or when a physical blockage prevents sheet movement. By following basic cleaning procedures, you can effectively clear this fault and restore normal printing operations.

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Common causes

  • 1Dirty paper sensor: Dust and debris blocking the optical sensor beam.
  • 2Worn rollers: Loss of traction leading to failed paper pickup.
  • 3Physical blockage: Paper scraps or foreign objects in the path.
  • 4Motor drive failure: Mechanical wear preventing the movement of the feed mechanism.

Solutions

Quick Diagnosis

Error 390 indicates that the printer cannot successfully pull paper from the tray. If you notice grinding sounds, check for small pieces of paper or debris blocking the path.

Step-by-Step Solution

  1. Power off the device and disconnect the power cord.
  2. Remove the primary paper tray and inspect for obstructions.
  3. Verify the paper guides are correctly set to the sheet size.
  4. Clean the feed rollers with a lint-free cloth and isopropyl alcohol.
  5. Reconnect and restart the printer.

Prevention and Maintenance

Avoid using damp or low-quality paper, which can deposit residue on rollers. Consistent maintenance every few months will extend the life of the feed system. Genuine toner cartridges are recommended to prevent internal dust buildup.

When to Call a Technician

If cleaning and path inspection do not clear the alert, a sensor or the drive motor may have suffered a permanent mechanical failure requiring replacement parts.

Technical Specifications

  • Technology: Monochrome Laser
  • Speed: Up to 47 ppm
  • Connectivity: USB 2.0, Ethernet 10/100/1000
  • Feeding capacity: 630 sheets (expandable)
  • Compatible consumable: Toner cartridge 45439202
  • Recommended use: High-volume corporate offices
  • Drivers / official firmware

Steps to follow

  1. 1

    Power off and reset

    Turn off the device and unplug the power cable for 60 seconds to reset the sensors.

  2. 2

    Tray check

    Remove the paper tray and ensure no debris or clips are obstructing the path.

  3. 3

    Clean rollers

    Gently clean the visible feed rollers with a soft, lint-free cloth.

Frequently asked questions

This error signifies a paper feed detection failure, often caused by sensor blockage or worn-out feed rollers.

It is not critical but will stop all print jobs until the paper path is cleared and the sensor is reset.

It uses the B721 high-yield toner cartridge series. Genuine consumables are recommended for best performance.

Perform regular roller cleaning every 50,000 prints and store paper in a low-humidity environment.

OKI B721n Error 390: Troubleshooting and Solutions | Vimazdev