Honeywell Home Security F27 Error Code Fix Guide

Here’s the no-nonsense sequence that matches what the manuals and alarm companies expect you to do. Go in order. If a step feels out of your depth, stop and call your monitoring company.

• 1. Disarm the system. Get it to a ready/idle state. No alarms, no tests running.
• 2. Check your internet or cell coverage first.
  • Wi‑Fi or Ethernet system: Make sure phones/laptops on the same router can reach the internet.
  • Cellular-only communicator: Stand near the panel and check your phone’s signal. If cell service is garbage there, the communicator will struggle too.
• 3. Power-cycle your modem/router.
  • Unplug modem and router for 30 seconds.
  • Plug them back in and wait a full 5 minutes.
  • Give the alarm panel another 5–10 minutes to reconnect and see if F27 clears.
• 4. Reseat the communicator’s network connection.
  • Ethernet/IP: Push the Ethernet plug (RJ45) firmly into the communicator and router. Try a different router port if you have one.
  • Wi‑Fi: On the keypad/touchscreen, open Network/Wi‑Fi settings, then:
    • Forget/remove the old Wi‑Fi network.
    • Reconnect to your 2.4 GHz SSID (most panels do not like 5 GHz).
    • Re-enter the Wi‑Fi password slowly and double-check it.
• 5. Reboot the alarm panel the proper way. Low-voltage, but do it clean.
  • Disarm the system.
  • Unplug the wall transformer (often a beige/white brick near the panel; it may be screwed to the outlet).
  • Open the metal/plastic can for the main panel and disconnect one battery lead.
  • Wait 60 seconds.
  • Reconnect the battery.
  • Plug the transformer back in.
  • Wait 5–10 minutes for it to fully boot and attempt to reconnect. Then check if F27 is gone.
• 6. Verify your monitoring/communication account is active.
  • If you changed alarm companies, cancelled, moved house, or switched internet/cell providers, the communicator might be deactivated or not provisioned for the new setup.
  • Call your monitoring company and say: ‘I’m seeing F27 communication fault on my Honeywell panel. Do you see my communicator online on your side?’
  • They can check if the SIM, IP account, or registration is live.
• 7. Follow the manual’s last step: dealer/service call.
  • If F27 survives all the network checks and a full reboot, the communicator itself may be failing.
  • It might also be locked to a previous dealer and simply will not re-register without their involvement.
  • The SIM in a cellular communicator could be dead, out-of-date tech (old 3G), or deactivated by the carrier.

  At that point, the official answer is: schedule a service call. A Honeywell/Resideo-friendly tech can run a communicator test, re-register it, or swap in a new module.

If you have no idea whether yours is IP, cell, or Wi‑Fi: don’t poke around blindly inside the cabinet. Stop after the reboot and let your monitoring company tell you exactly what hardware you have.