Garmin’s System Software 23.40 is a stable update for its flagship smartwatch platform that specifically addresses an optical heart-rate sensor failure. Garmin’s October 13, 2026 release note says the update also repairs a crash tied to active heart-rate broadcasting and a silent-mode notification bug. The clearest confirmed recipients in current rollout reporting are the fēnix 8 and Tactix 8, although Garmin is distributing the software in stages.
What System Software 23.40 changes
The central fix is stated plainly in Garmin’s official changelog: “Fixes optical heart rate sensor not working.” On affected watches, the optical sensor could stop recording wrist-based heart rate after the preceding stable release, version 23.39. Version 23.40 is intended to restore that function through software rather than requiring an external sensor.
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Garmin lists three additional changes:
- Active heart-rate broadcasting: fixes a crash when enabling the feature through Garmin Connect Mobile (GCM).
- Silent mode: fixes notifications that continued to make sound when silent mode was enabled.
- General stability: resolves other minor issues without further detail in the public changelog.
The official release post is dated October 13, 2026. Reporting published October 14 describes 23.40 as the successor to 23.39 and confirms the staged rollout.
Which Garmin watches are receiving 23.40?
Current coverage most clearly confirms the Garmin fēnix 8 and Tactix 8. Garmin’s wider feature-update documentation lists the fēnix 8, fēnix 8 Pro, fēnix E, Enduro 3, tactix 8 and quatix 8 as supported smartwatch platforms, but that platform list should not be read as proof that every model had version 23.40 at the same time.
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- For your active lifestyle, a built-in speaker and mic let you make and take phone calls from your wrist when your watch is paired to your smartphone — and you can even use your smartphone’s voice assistant to respond to text messages and more
| Model or family | 23.40 availability in current reporting | What owners should know |
|---|---|---|
| fēnix 8 | Confirmed among the first recipients | The optical-heart-rate fix directly addresses the reported failure on this flagship family. |
| Tactix 8 | Also reported as receiving the update | Availability can still vary by rollout stage and region. |
| fēnix 8 Pro | Different cadence or not yet confirmed in the October 14 report | Check Garmin’s update channels rather than assuming immediate eligibility. |
| fēnix E | Different cadence or not yet confirmed | Model, region and staged-release timing affect visibility. |
| Enduro 3 | Different cadence or not yet confirmed | Use Garmin Connect or Garmin Express to check. |
| quatix 8 | Different cadence or not yet confirmed | A supported platform is not the same as simultaneous 23.40 delivery. |
Case size, display type and regional software eligibility can differ within a family. If 23.40 does not appear immediately, that does not by itself indicate a fault.
How to check for and install the update
- Check from the watch: open the watch’s software-update controls and run a manual check. If 23.40 is offered, accept the download and installation prompts.
- Sync with Garmin Connect: open Garmin Connect Mobile, keep the watch paired, and complete a sync. Garmin can deliver eligible software through the connected phone; keep the watch charged while it installs.
- Use Garmin Express: connect the watch to a computer, open Garmin Express, select the device, and run the available software update check. Follow the on-screen installation steps.
- Allow for staged delivery: repeat the check later if the watch is eligible but the package is not yet visible. Garmin’s staged rollout means two owners of similar watches may see different timing.
After installation, allow the watch to restart fully before judging sensor behavior. Check a normal wrist-heart-rate reading and, if you use it, test active heart-rate broadcasting from Garmin Connect Mobile.
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Does 23.40 fix the battery-drain or display-brightness problem?
Not according to the information currently available. The 23.40 changelog names the optical heart-rate failure, active-broadcasting crash, silent-mode behavior and minor issues. It does not identify a separate display-brightness or battery-drain problem as fixed. Current reporting treats that issue as a separate matter Garmin had discussed independently, so owners should not install 23.40 expecting a guaranteed battery or display remedy.
What if heart rate still does not record?
First verify that the watch completed 23.40 installation and has restarted. Then sync again through Garmin Connect or Garmin Express and test the wrist sensor during ordinary wear. If the optical reading remains unavailable after the update, document the watch model, software version and symptoms before contacting Garmin support; the public release note establishes the intended software fix, but it does not provide a repair-rate or failure-rate guarantee.
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- Advanced multisport GPS smartwatch for athletes/adventurers features a bright 1.3” AMOLED display with scratch-resistant sapphire lens, durable steel or titanium bezel and a built-in LED flashlight for after-dark visibility
- Power up your body’s performance, endurance and resistance to injury with targeted strength training plans, real-time stamina tracking, sport-specific workouts and a full range of built-in sports apps
- Battery performance: up to 10 days in smartwatch mode; up to 28 hours in GPS mode
- Your training readiness score is based on sleep quality, recovery, training load and HRV status to determine if you’re primed to go hard and reap the rewards (data presented is intended to be a close estimation of metrics tracked)
- For your active lifestyle, a built-in speaker and mic let you make and take phone calls from your wrist when your watch is paired to your smartphone — and you can even use your smartphone’s voice assistant to respond to text messages and more
An external monitor such as Garmin’s separately sold HRM 600 can provide another source of heart-rate data for compatible activities. It is optional and is not required for the 23.40 repair.
Quick Recap
Best Value
- Advanced multisport GPS smartwatch for athletes/adventurers features a bright 1.3” AMOLED display, stainless steel bezel, enhanced graphical interface and a built-in LED flashlight for after- dark visibility
- Power up your body’s performance, endurance and resistance to injury with targeted strength training plans, real-time stamina tracking, sport-specific workouts and a full range of built-in sports apps
- Battery performance: up to 10 days in smartwatch mode; up to 28 hours in GPS mode
- Your training readiness score is based on sleep quality, recovery, training load and HRV status to determine if you’re primed to go hard and reap the rewards (data presented is intended to be a close estimation of metrics tracked)
- For your active lifestyle, a built-in speaker and mic let you make and take phone calls from your wrist when your watch is paired to your smartphone — and you can even use your smartphone’s voice assistant to respond to text messages and more
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- Battery performance: up to 48 days of battery life in smartwatch mode with solar charging (assumes all-day wear with 3 hours per day outside in 50,000 lux conditions) and up to 149 hours in GPS mode with solar charging (assumes continuous use for entire period in 50,000 lux conditions) — all with an always-on display, so you’re ready to take on the toughest challenges
- Power up your body’s performance, endurance and resistance to injury with targeted strength training plans, real-time stamina tracking, sport-specific workouts and a full range of built-in sports apps
- Your training readiness score is based on sleep quality, recovery, training load and HRV status to determine if you’re primed to go hard and reap the rewards (data presented is intended to be a close estimation of metrics tracked)
- For your active lifestyle, a built-in speaker and mic let you make and take phone calls from your wrist when your watch is paired to your smartphone — and you can even use your smartphone’s voice assistant to respond to text messages and more
What owners should take from the release
- Version 23.40 is the first Garmin release in this sequence to explicitly name the optical heart-rate sensor failure and its fix.
- The same release addresses active heart-rate broadcasting crashes and silent-mode notification behavior.
- fēnix 8 and Tactix 8 are the clearest confirmed early recipients; other listed platforms may follow on a different schedule.
- Checking the watch, Garmin Connect and Garmin Express is more reliable than waiting for every model to update simultaneously.
- The release does not confirm a fix for the separately discussed display-brightness or battery-drain issue.
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