Garmin Forerunner F43 Error Code Fix

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What This Error Means

F43 on a Garmin Forerunner = system fault / firmware crash.

Garmin doesn’t publicly document this code, but in the real world it pops up when the watch hits a software or storage error and can’t start or run workouts normally.

Official Fix

Here’s the straight-from-the-manufacturer style flow. Do it in this order:

  • 1. Force a reboot
    Hold the Light/Power button for about 15–30 seconds until the screen goes black, then release and press it again to power back on. This clears a simple crash.
  • 2. Give it a solid charge
    • Snap the watch into the charger and plug into a stable USB power source (not a flaky hub).
    • Let it sit at least 30–60 minutes, even if the screen looks frozen at first.
    • Low or unstable voltage during boot can trigger repeat F43 errors.
  • 3. Update the firmware
    • Connect the watch to a PC/Mac with the Garmin cable.
    • Install and open Garmin Express.
    • Add/select your device and apply all pending software updates.
    • Safely eject, then reboot the watch again.
  • 4. Back up, then do a normal factory reset (if the menus are still usable)
    • Sync recent activities to Garmin Connect first so you don’t lose runs/rides.
    • On the watch, go to roughly: Settings > System > Reset.
    • Pick the option that says Delete Data and Reset Settings or similar.
    • Let it wipe and reboot, then test for the F43 error.
  • 5. Master reset (when menus are dead)
    If you can’t even get into Settings:
    • Power the watch off (hold Light/Power until it dies).
    • On many Forerunner models you can do a hard reset by holding specific buttons while turning it on (for example Start/Stop + Back/Lap on power-up), but the combo varies by model.
    • Check Garmin’s official support page for your exact model’s “master reset” button combo and follow that.
  • 6. If F43 keeps coming back
    • Contact Garmin Support with your model and the F43 code.
    • If they can’t clear it remotely, they’ll usually offer a flat-fee repair or replacement, especially if it’s in or just out of warranty.

If you’re under warranty or close to it, this path is exactly what Garmin will walk you through before authorizing a swap.

The Technician’s Trick

When reset-after-reset doesn’t kill F43, a lot of techs assume file system corruption – one bad activity file can crash the watch. Here’s the behind-the-counter move:

  • 1. Force it to mount as storage
    • Connect the watch to a PC/Mac with the USB cable.
    • Try a different cable and USB port if the computer doesn’t see it.
    • Wait: on some models it takes 10–30 seconds before the “GARMIN” drive shows up.
  • 2. Back up everything first
    • Open the GARMIN drive on your computer.
    • Copy the entire contents to a folder on your desktop. This is your safety net.
  • 3. Nuke the likely corrupt files
    Inside the GARMIN drive:
    • Open the Activities folder. Sort by Date Modified.
    • Delete the last few .FIT files (the most recent workouts – they’re usually the broken ones).
    • Also check NewFiles and Workouts folders and delete anything obviously half-synced or very recently added.
  • 4. Let Garmin Express rebuild it
    • Safely eject the watch and disconnect.
    • Reconnect, open Garmin Express, and look for an option to reinstall or repair device software.
    • Run that, then eject and reboot the watch.
  • 5. Clean the power path
    This one’s simple but surprisingly effective:
    • Clean the charging contacts on the back of the watch and on the cable with a cotton swab and a bit of isopropyl alcohol.
    • Let it dry, reconnect, and give it a full charge cycle, then test again.

If the watch boots clean after this and F43 doesn’t return over a few workouts, you dodged a mainboard replacement.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: Watch is under ~4–5 years old, no water damage, F43 only showed up after a crash or update, and a reset/firmware reload brings it back or Garmin offers low-cost flat-fee service.
  • ⚠️ Debatable: Older Forerunner, out of warranty, F43 keeps returning but you really like the watch – compare Garmin’s repair quote vs. the price of a newer model with better battery and GPS.
  • ❌ Replace: F43 won’t clear, watch won’t power even on a known-good charger, there’s clear impact or water damage, or Garmin’s repair price is close to a new Forerunner – put the money into a fresh unit.

Parts You Might Need

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See also

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