Your Fenix 9 Pro is making a decision about your run that Garmin never put in the manual, and independent testing just caught it happening.
About twenty seconds into a GPS activity, the watch starts tracking everything: GPS, GLONASS, Galileo, BeiDou, QZSS, on both the L1 and L5 frequency bands. Then GLONASS disappears. It doesn't come back for the rest of the session.
The watch cut an entire satellite constellation loose mid-run to save power. The question everyone asked first, is this a new GPS chip behaving differently, doesn't hold up. Which makes the real story more interesting, not less.
What the testing actually found
The5krunner published a GPS Event export analysis from a Fenix 9 Pro recorded under tree cover in Normal mode, and the log tells a clean story. Everything switches on at the start. Roughly twenty seconds in, GLONASS drops out and stays out, while the watch continues toggling between single-frequency and dual-frequency tracking, adding and cutting the L5 band as conditions change.
The author worked through the data with Michael George of gps-details, the person who maintains the most detailed public mapping of which GNSS chipsets sit inside which Garmins. Their conclusion: Garmin's watches have quietly done this since the Fenix 7 in 2022. DC Rainmaker described the same behavior at the time, Garmin "switching between GPS, GLONASS, GALILEO, BeiDou, and QZSS based on the quality of the satellites from each." What's new is confirmation it's still running on the Fenix 9 Pro, and the first detailed look at exactly how it plays out in a session log.
Why GLONASS gets cut first is not a mystery. It's typically the least accurate of the four major constellations. Dropping it saves power with minimal effect on position quality, leaving more of the budget for GPS, Galileo, and BeiDou. The evidence suggests the watch sheds it once signal quality has measurably deteriorated, rather than preemptively.
The new-chipset theory, and why it collapses
Here's the part worth slowing down on, because the obvious explanation turned out to be wrong, and the person who proposed it said so publicly.
A firmware version difference on the Fenix 9 suggested a new GPS chipset, which would neatly explain new behavior. Then the same firmware version turned up on the Fenix 8, whose chip is already confirmed unchanged: the Synaptics SYN4778, identified in teardowns and logged in FIT files as GNSS product number 4536. One firmware string doing double duty on two generations is exactly what you'd expect if the chip never changed.
The teardown community has been circling this since launch. A component-by-component comparison making the rounds on r/the5krunner noted that "only the Fenix 9 Pro is CONFIRMED to run a newer chip," and even that confirmation applies to the main processor, the one behind the faster maps we covered in our Fenix 9 map lag piece, not the GNSS receiver. The GPS chip column for both Fenix 9 models: TBC. Garmin's own marketing still says "dual-frequency tracking across five satellite systems," word-for-word identical to the Fenix 8's spec sheet.
And Garmin's Connect IQ developer documentation quietly confirms the behavior is engineered, not emergent. It lists named, fixed GNSS configurations developers can request: GPS alone, GPS plus GLONASS, GPS plus Galileo, GPS plus BeiDou, and two all-constellation combinations. Sitting alongside those is AutoGNSS, the dynamic mode doing the shedding in the log above. The software architecture already assumes a Garmin device might need to drop constellations mid-activity.
The changes Garmin did make, hiding in plain sight
While everyone was watching the Pro's new processor, the satellite settings got reworked. The old names are gone:
- Auto Select is now Normal (SatIQ dynamic selection, unchanged behavior)
- All + Multi-Band is now Max Accuracy (full multi-band, all constellations, unchanged)
- GPS Only is now Extended Battery (changed: now GPS + Galileo, never GPS alone)
- UltraTrac is now Max Battery (unchanged)
Two things buried in that table. First, GPS-only mode no longer exists in any form. Even the battery-saver configuration bundles Galileo in, because Garmin evidently decided bare GPS was costing more in accuracy than it saved in power. Second, SatIQ isn't a separate setting anymore. It's baked into every mode now, managed automatically. Garmin is standardizing all future battery claims on this four-mode scheme, which DC Rainmaker notes is partly so Garmin doesn't have to re-underwrite battery numbers for every older model.
Reddit did not take that second change quietly. In the r/Garmin thread on the Fenix 9 features backport, user -Radiation pushed back hard on losing forced multi-band: "A Garmin advantage is that we used to have settings to set up almost everything as we like, this is more like Apple deciding we can't use the device a certain way." Their specific complaint, tested with two watches side by side, is that SatIQ doesn't switch fast enough between dense buildings or heavy tree cover, and they'd rather eat the battery cost than trust the automation. Another commenter, Jordan11, called losing forced multiband "a pretty big deal," while an Enduro 3 owner argued the opposite: "Removing a setting that has no benefit, and only has a cost seems prudent."
That's the real tension the constellation shedding exposes. Garmin is betting its automated satellite management is good enough that you should stop being allowed to override it. Some owners are not ready to make that bet.
Does the shedding actually hurt accuracy?
The honest answer, from the testing so far: no.
The5krunner's own runs under significant tree cover with GLONASS shed found the Fenix 9 Pro accurate. And a remarkable side-by-side post on the Garmin forums this week, a Fenix 8 Solar owner who ran a Fenix 9 Pro Solar on the opposite wrist for days, concluded GNSS performance was "excellent on both watches" with "no clear generational leap in absolute positioning quality." The Fenix 9 track came out slightly smoother and slightly shorter, which the author read as stronger positional filtering rather than better raw satellite performance.
So there's the trade-off, stated plainly: the watch trades a weaker constellation for battery, keeps position quality intact or better, and filters the result into a cleaner track. If you're the type who wants the rawest possible data, that filtering is the thing to watch, not the missing GLONASS.
Early battery impressions from owners are consistent with the math. A Fenix 9 Pro 43mm owner on r/GarminFenix reported losing just 3% on a one-hour hike in Normal mode, with the community doing the arithmetic that Normal mode on that model is rated around 18 hours of activity tracking.
What about tri-band?
Not yet, and this is a dual-frequency story. Garmin's marketing language is unchanged from the Fenix 8, and the GPS log confirms L1 plus L5 only. The case for tri-band reaching Garmin's flagships has been building all year, and it hasn't happened here. Given that COROS and Garmin's rivals are moving on multi-band tech, it's a safe bet it comes eventually. Just not on the Fenix 9.
Bottom line
The Fenix 9 Pro isn't running new GPS silicon, and it isn't doing anything Garmin watches haven't done since 2022. What it is doing is shedding that behavior into the open for the first time, via a renamed satellite mode scheme where SatIQ runs everything and your override options quietly shrank.
If you're coming from a Fenix 7 or 8 and wondering whether your tracks will change: they won't, much. The constellations that matter stay on, the accuracy testing says the results hold up under tree cover, and the battery wins are real. The one thing worth internalizing is the philosophy shift. Garmin has decided the watch knows better than you which satellites to trust, and this generation is the first where you can no longer argue with it.
Watch for the community's own GPS Event exports as more Fenix 9 units hit wrists. If the shedding pattern holds across owners and conditions, expect Garmin to keep pushing automation and keep trimming manual controls, on this watch and every one after it.