Honeywell Home Security F33 Fix: Error Code Guide

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What This Error Means

On most Honeywell / Resideo home security systems, F33 (or FAULT 33 / CHECK 33) means the device on zone 33 is in trouble.

That zone is usually a single sensor (door contact, window contact, motion, or glassbreak) the panel now thinks is open, tampered, low on battery, or not talking to the system.

What is actually happening: the panel has lost a clean, closed signal from the sensor programmed as zone 33, so it flags F33 and may refuse to arm.

Official Fix

This is the play the manual wants you to run.

  • 1. See what zone 33 actually is.
    On text keypads, hit [*] or read the scrolling text. You’re looking for something like “ZONE 33 BACK DOOR” or “33 LIVING ROOM MOTION”. That label tells you exactly which device is angry.
  • 2. Check the obvious at that device.
    Door/window contact: door fully shut, sensor and magnet lined up tight (small gap, ideally < 1/4"). Motion/glassbreak: still firmly mounted, not soaked, smashed, painted over, or dangling off the wall/ceiling.
  • 3. Swap the battery if it’s wireless.
    Pop the cover with a small screwdriver, note the battery type and orientation, put in a fresh matching battery, and close the cover firmly so the tamper switch is pressed. A weak battery is one of the most common causes of an F33 on wireless zones.
  • 4. Close, then clear the fault.
    Make sure the door/window is closed and nobody is walking in front of motions. Then disarm twice in a row (for many panels: [Code] + OFF twice) or hit Clear on a touchscreen. Give it up to 90 seconds for the panel to re‑check zone 33 and drop the code.
  • 5. If F33 stays, the sensor or wiring is likely bad.
    Wired: look for broken or pulled‑out wires at the sensor or inside the metal panel can. Wireless: if a new battery didn’t help and it still throws F33, the transmitter is probably failing and needs replacement and re‑enrollment by you or your alarm dealer.

If the system is monitored or dealer‑owned, they may have to program any replacement device into zone 33 for you. Don’t delete or reprogram zones blindly unless you know the panel logic.

The Technician’s Trick

Here’s how techs keep things moving when F33 won’t clear but you still need the system usable.

  • 1. Hard reset the wireless sensor.
    Pop the sensor cover, pull the battery for 10–15 seconds, gently pinch the battery clips a bit tighter if they’re loose, put in a new battery, and snap the cover fully closed. Then open and close the door/window once to force a fresh signal to the panel.
  • 2. Pull the magnet in closer.
    If F33 only shows when the door is “closed”, the gap is borderline. Loosen the magnet, slide it closer to the sensor, and retighten. Shim with a bit of cardboard or tape if the surfaces don’t line up cleanly. This fixes a lot of “mystery” faults after a door has sagged a few millimeters.
  • 3. Bypass zone 33 so the rest can arm.
    Use your code + BYPASS (or the “Bypass Zones” menu on touchscreens), select zone 33, then arm like normal. The system ignores that bad sensor so you’re not locked out of using the rest of the system. Remember: that one opening or motion is effectively unprotected until you fix it and remove the bypass.
  • 4. Reboot the panel if the fault looks bogus.
    If everything checks out and F33 still sticks around, power‑cycle the panel: unplug the transformer, disconnect the backup battery in the metal can, wait 60 seconds, then reconnect battery and plug back in. Don’t do this during an active alarm or a monitoring test call.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: Single zone F33 on an otherwise stable system, especially if it’s just a door contact or motion and likely a battery or $20–$40 sensor swap.
  • ⚠️ Debatable: Panel is 10–15 years old and you’re chasing faults on multiple wireless zones; worth comparing the cost of several new sensors versus starting to budget for a modern system upgrade.
  • ❌ Replace: Random F‑codes across many zones, keypads freezing, or a quoted repair that runs more than about half the price of a new system with app/remote features.

Parts You Might Need

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See also

Dealing with more than just your alarm system? These error code guides might save you more time: