Honeywell Home Security F31 Error Code Fix

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What This Error Means

On most Honeywell Home / Ademco-style alarm panels, F31 means “Zone 31 Fault.”

Translation: the sensor on zone 31 (door, window, motion, etc.) looks open, tampered, or dead, so the panel will not show READY and will refuse to arm.

Official Fix

Manual-approved steps; do them in this order.

  1. Kill the beeping.
    • Enter your 4-digit user code, then press OFF.
    • Do it twice: CODE + OFF + OFF. Noise stops, fault stays.
  2. Identify Zone 31.
    • Read the keypad line that mentions 31. Often it will say something like “31 FRONT DOOR” or “31 HALL MOTION.”
    • If you see only F31 or ZONE 31, check any zone list sheet or the label inside the metal panel box.
  3. Check the hardware.
    • Door / window contact: Door or window fully closed; magnet and sensor close and lined up; nothing loose or cracked.
    • Motion: Cover snapped tight; no tape, paint, or damage on the lens.
    • Wired device: Light tug on each wire at the sensor and at the panel; no broken or pulled-out conductors.
  4. Swap the battery (wireless only).
    • Open the sensor on zone 31.
    • Match the battery type and polarity exactly and put in a fresh one.
    • Close the cover firmly so the tamper switch is pressed.
  5. Clear the fault.
    • Make sure the door/window is closed and no one is in front of the motion.
    • Wait 30 seconds, then enter CODE + OFF + OFF.
    • If the display shows READY or READY TO ARM and F31 is gone, you are done.
    • If F31 stays, the sensor, its wiring, or its programming is bad.
  6. When the manual says call for service.
    • Zone is closed, cover is on, new battery, but F31 will not clear.
    • At that point the official fix is:
      • Replace the sensor on zone 31, and/or
      • Have a tech check wiring and zone programming in installer mode.

The Technician’s Trick

How techs keep your system usable while the bad zone waits for parts.

  • Bypass Zone 31.
    • On most Honeywell Vista / Ademco-style panels:
    • Enter your 4-digit user code.
    • Press 6 (BYPASS).
    • Enter 31.
    • Confirm the display shows “31 BYPASSED,” then arm as normal.
    • The rest of the system works; anything on Zone 31 is unprotected until you un-bypass and fix it.
  • Adjust a touchy door/window magnet.
    • If F31 appears only when the door is barely closed, the gap is too large.
    • Loosen the magnet, slide it closer to the sensor, tighten it.
    • Shim with thin plastic or cardboard if you need a bit more height or alignment.
  • Power-cycle to clear a ghost fault (hardwired panels only).
    • Unplug the alarm transformer from the wall.
    • Disconnect one lead of the 12V backup battery in the metal can.
    • Wait 30 seconds, reconnect the battery, plug the transformer back in.
    • If you are monitored, warn your monitoring company first so they do not treat it as a problem signal.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: One sensor on Zone 31 is acting up, the system is under about 10–12 years old, and everything else works fine. Swap the battery or sensor and keep the system.
  • ⚠️ Debatable: You are seeing repeating faults on several zones, wiring looks hacked together, or the panel is 12–15+ years old. Get a repair quote and compare it to the cost of a modern replacement system.
  • ❌ Replace: The main board or multiple keypads are failing, F-codes keep coming back, and you are already paying for multiple truck rolls. Do not chase F31 forever; price a new system.

Parts You Might Need

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See also

Chasing other weird codes on your smart gear? These quick guides help too: