On this page
01. Check the sensor02. Re-enrol badly enrolled fingers03. Difficult fingers04. Other causes05. When to replace06. A typical scenario07. Common mistakes08. Quick checklist09. Frequently asked questions
Clean the sensor with a soft dry cloth, re-enrol the finger on a different finger and with better technique, remind staff to press flat and firm, and keep the terminal away from direct sun and dust.
Key takeaways
- Clean the glass.
- Re-enrol with good technique.
- Enrol two or three fingers.
- Avoid direct sun and moisture.
01Check the sensor
- Wipe with a soft, dry, lint-free cloth.
- Do not use harsh chemicals.
- Look for scratches or oil build-up.
- Keep it out of direct sunlight, which confuses optical sensors.
02Re-enrol badly enrolled fingers
Delete the fingerprint and enrol again with a clean finger. See enrol a fingerprint. Press firmly and flat three times with the same angle.
03Difficult fingers
- Dry skin: a light touch of moisture helps.
- Wet or sweaty fingers: wipe dry.
- Worn prints from manual work: use a different finger or consider face or card (worn fingerprints).
- Cuts and plasters: use a different finger.
04Other causes
- Sensor damage after a knock or liquid spill.
- Firmware issues; ask your supplier about updates.
- Very hot or dusty rooms; protect the terminal.
05When to replace
If cleaning, re-enrolment and a few staff all fail, the sensor may be worn. We can test it. Message us on WhatsApp.
06A typical scenario
A hardware shop's workers had rough, worn fingers and kept being rejected. Cleaning the sensor, enrolling three fingers each, and giving a short training solved most cases; two workers moved to card punching.
Illustrative example based on common cases, not a named customer.
07Common mistakes
- Cleaning with strong chemicals.
- Enrolling once in a hurry.
- Placing the terminal in sunlight.
- Ignoring training.
- Expecting every finger to work.
08Quick checklist
- Clean the glass
- Re-enrol
- Two or three fingers
- Check light
- Train staff
- Consider alternatives
09Frequently asked questions
Why does it work for some staff only?
Skin type, dryness and technique differ. Re-enrol and train.
Can I make it more tolerant?
Some firmware allows a match-threshold setting. Lower security equals easier matching but more false accepts; change with care.
Do I need to clean it every day?
A wipe each week is plenty; more in dusty sites.
Is a face terminal better?
For worn hands, yes. See fingerprint or face.
This guide is part of our ZKTeco K40 and ZKBio Time.Net series. For the full start-to-finish walkthrough with screenshots, read How to Configure a ZKTeco K40 Pro with ZKBio Time.Net.
ZKTeco and ZKBio are trademarks of ZKTeco Inc. Menu names on the K40 Pro and in the software vary slightly by firmware and software version; where yours differ, look for the nearest match. Qyvea is a ZKTeco reseller and installer in Kenya.
