U4fi-800R

Fujitsu fi-800R Error U4: Solution and Causes

The Fujitsu fi-800R error U4 is a safety alert indicating that the scanner's cover is not detected as closed. This security feature protects the high-precision optics while the motor is active. Knowing why my Fujitsu fi-800R error U4 occurs is simple, as it is usually a physical blockage or dust on the sensor.

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Common causes

  • 1Debris in the hinge.
  • 2Dirty closure sensor.
  • 3Misaligned top cover.
  • 4Worn micro-switch.

Solutions

Quick Diagnosis

Error U4 triggers if the lid isn't fully shut or if debris blocks the closure sensor. Check for stability of the cover.

Step-by-step Solution

  1. Open the top cover.
  2. Clean the closure sensor near the hinge.
  3. Close firmly until it clicks.
  4. Reset via software.

Prevention and Maintenance

Keep rollers and sensors clean weekly. Don't leave the lid open.

When to call a technician

If closing it firmly doesn't work, the micro-switch may be broken.

Technical Specifications

Steps to follow

  1. 1

    Open cover

    Fully open the scanner top cover.

  2. 2

    Inspect sensors

    Clean the closure sensor with a dry cloth.

  3. 3

    Firm closure

    Close the lid until you feel the sensor click.

Frequently asked questions

The safety sensor detects that the cover is not correctly closed.

No, scanning is locked for safety until the cover is properly secured.

No, this is a mechanical error.

Close the cover firmly but gently to protect the sensor.