Step by step

  1. Press the test button

    Test each alarm using the manufacturer's instructions. It should sound clearly.

  2. Check the status

    Look for a low-battery chirp, fault light or expired replacement date.

  3. Keep it clean

    Gently remove surface dust as the manufacturer recommends; do not paint or cover an alarm.

  4. Replace what has expired

    Change replaceable batteries or the whole unit according to its instructions, and test again.

  5. Keep a routine

    Set a regular reminder and show everyone in the home what the alarm sounds like.

Know when to stop

When to stop and call a professional

If a CO alarm sounds, treat it as a real warning: get everyone into fresh air, seek medical advice if anyone feels unwell, and contact the gas emergency service. Never ignore or silence an unexplained alarm.

Check the official guidance for current safety rules and obligations.

General information for a UK home; always follow your product instructions and current local rules. Images are illustrative, not technical diagrams.