Honeywell Home Security F23 Error Code Guide (Real-World Fix)

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What This Error Means

F23 on a Honeywell Home security system = Zone 23 fault.

Your panel thinks the device programmed as zone 23 (usually a door/window contact or motion) is open, missing, or tampered, so it throws F23 and may refuse to arm or keeps beeping at you.

Official Fix

What the manuals and monitoring companies expect you to do:

  • Quiet the beeping first. On most Honeywell keypads: enter your 4‑digit user code, then press OFF twice. F23 will still show, but at least it shuts up.
  • Figure out what zone 23 actually is. Check the keypad display for a label (like “Z23 KITCHEN WINDOW”), the zone list sticker on the panel door, or your install paperwork.
  • Go to that sensor and make sure it’s really closed. Close the door/window firmly. For a door/window contact, the sensor and magnet should sit almost touching (gap usually under 1/4–1/2 inch).
  • Inspect the sensor and magnet. Look for anything loose, cracked, or hanging by tape. If the magnet slid away, move it back so it lines up directly with the sensor.
  • For a wireless sensor:
    • Carefully pop the cover (small slot on the side/bottom).
    • Make sure the tamper switch is pressed when the cover is on.
    • Replace the battery with the exact same type (match the number on the old battery).
    • Snap the cover back fully so the tamper is closed.
  • For a wired contact:
    • Look for a broken or pulled wire at the contact.
    • If the contact is smashed or the wire’s hanging out, it probably needs replacement and re-termination at the panel.
  • Test and clear the error. With the sensor closed, wait 30–60 seconds, then enter your code + OFF again. If the sensor is healthy, F23 should clear.
  • Still stuck on F23? At this point the official advice is: call your alarm company or a Honeywell/Resideo dealer to test the zone wiring/programming and replace the sensor if needed.

The Technician’s Trick

When you call a real alarm tech, here’s the kind of “inside baseball” they actually use on F23.

  • 1. Bypass zone 23 so you can still arm. This does not fix the sensor; it just takes it out of service.
    • On many Honeywell keypads: enter your user code, press the BYPASS key (often the [6] key), then enter 23 for the zone number, then arm as normal.
    • If you don’t see a BYPASS key or don’t know your code, skip this and don’t guess; too many wrong tries can cause more trouble.
  • 2. Hard reboot a glitchy panel. Sometimes F23 sticks even after the sensor is fine.
    • Tell your monitoring company you’re powering down (if you’re monitored).
    • Unplug the transformer (or turn off the breaker) powering the panel.
    • Open the metal can/plastic can for the main board and disconnect the backup battery leads.
    • Wait 30–60 seconds.
    • Reconnect the battery, then plug the transformer back in.
    • Let the panel boot, enter your code + OFF to clear trouble, then see if F23 comes back.
  • 3. Swap sensors to prove what’s bad. If you have another identical door/window sensor:
    • Swap the questionable sensor on zone 23 with a known-good one from a less important window.
    • If the F23 error follows the sensor, the sensor is bad.
    • If the error stays on zone 23 no matter which sensor you use, the problem is wiring or panel/receiver side.
  • 4. Temporary “panel-side” fix for wired zones. Pros will sometimes land a new contact right at the panel with the proper end-of-line resistor, just to get the zone stable until a full rewire can be done.

If anything above sounds like too much, stop there and call a pro. Better a service call than a dead alarm system.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: One bad zone (F23 only), system under ~10–12 years old, and it’s clearly a dead sensor, loose magnet, or battery. Expect $10–$40 in parts or ~$100–$200 for a service call.
  • ⚠️ Debatable: System around 12–15 years old, multiple wireless zones have already failed, or tech is talking about running new cable/reprogramming lots of zones. Compare 2–3 truck rolls vs. the cost of a modern panel upgrade.
  • ❌ Replace: Panel 15+ years old, no app support, keypads fading, several zones flaky (not just F23), or your monitoring company is already pushing a swap. Put the money into a new system instead of chasing constant F-codes.

Parts You Might Need

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See also

Dealing with F-codes or similar errors on other gear? These guides help you decode the mess: