Smart home · contact sensor

Door or window sensor says open when it is closed

A contact sensor can misread when magnet alignment, gap, orientation, battery or mounting has changed. Move the magnet near the sensor before deleting it from the system.

Direct answer

A contact sensor can misread when magnet alignment, gap, orientation, battery or mounting has changed. Move the magnet near the sensor before deleting it from the system.

What this covers

  • The observed symptom matches this record
  • Customer-accessible settings, connections and external components
  • Diagnosis before reset, deletion or component replacement

What it does not cover

  • ×A model-specific error code with a different documented meaning
  • ×Internal electrical, battery-cell, gas, refrigeration or sealed-component repair
  • ×A guarantee that every model exposes the same control label
Try in this order0 of 4 completed
  1. Capture the exact symptom

    Reversible

    Watch live status while slowly bringing the magnet to the marked side of the sensor.

  2. Run the smallest isolation test

    Reversible

    Replace the battery if low and realign within the specified gap using temporary tape for testing.

  3. Correct only the proven cause

    Reversible

    Remount securely after confirming the exact alignment; re-pair only if the sensor never changes state nearby.

  4. Verify before changing anything else

    Reversible

    Open and close ten times and confirm automations receive every event.

Evidence ledger

Sources behind this answer

Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.

Exact questions

Common follow-ups

What should I check before resetting anything?+

Watch live status while slowly bringing the magnet to the marked side of the sensor.

What is the safest isolation test?+

Replace the battery if low and realign within the specified gap using temporary tape for testing.

When should I stop troubleshooting?+

Do not defeat entry sensors used for safety/security; service damaged housings or wiring.

Change recordAug. 17, 2026 — Published as an independently scoped question with a distinct isolation test, verification and safety boundary; source boundary: Ring Help.
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