If you use a Garmin Forerunner 935, accurate elevation tracking is often as important as distance or pace. Elevation data adds context to your runs, hikes, or rides—showing not just how far you go, but how much you climb or descend. But what if your Garmin Forerunner 935 stops recording elevation? This can be frustrating, especially if you rely on that data for training, performance analysis, or sharing your achievements. This article will help you understand why this happens, how to fix it, and how to prevent it in the future. Let’s look at the real reasons behind elevation recording issues and what you can do about them.
Understanding Elevation Recording On Garmin Forerunner 935
The Garmin Forerunner 935 uses a barometric altimeter to measure elevation. This sensor detects changes in air pressure to estimate how high you are above sea level. It works differently from GPS-based elevation, which is often less accurate. If your 935 isn’t recording elevation, something is likely wrong with the barometer, its calibration, or the device’s software.
Many users notice missing or flat elevation data in their workout summaries. Sometimes, the watch shows the same elevation for an entire activity. In other cases, the graphs look strange or empty when you sync to Garmin Connect. Understanding what causes these issues can save you hours of frustration.
Common Reasons Garmin Forerunner 935 Fails To Record Elevation
Blocked Or Dirty Barometric Port
The Forerunner 935 has a small hole on its back or side—this is the barometric port. If dirt, sweat, sunscreen, or water blocks this port, the barometer cannot sense air pressure changes. As a result, elevation data becomes flat or missing. This is especially common for people who use their watch in dusty, muddy, or wet conditions.
Incorrect Device Settings
If elevation data is turned off or set incorrectly in the activity profile, the watch may not record elevation. This happens if you customize activity profiles or restore the device from a backup. Always check if elevation recording is enabled before each workout.
Outdated Or Corrupted Firmware
Garmin regularly updates device software to fix bugs. An outdated or corrupted firmware can cause many issues, including elevation problems. Sometimes, a failed update or interrupted sync will affect sensor functions.
Faulty Or Damaged Barometer
The barometer is a sensitive electronic part. If your watch was dropped, exposed to extreme moisture, or had a strong impact, the barometer might fail. This often leads to permanent loss of elevation data until the device is repaired.
Gps Settings And Data Recording
Some users switch between GPS-only and GPS+GLONASS or GPS+GALILEO. While the Forerunner 935 uses a barometer, GPS settings can still affect the overall track and sometimes confuse the data if the GPS signal is poor.
User Calibration Issues
If you manually calibrate the elevation and enter the wrong value, the watch will use that incorrect reference. This skews all elevation data until recalibrated or reset.
How To Fix Garmin Forerunner 935 Not Recording Elevation
1. Inspect And Clean The Barometric Port
Find the small hole—usually near the back button. Use a soft, dry toothbrush or a can of compressed air to gently clean it. Never poke sharp objects inside, as this can damage the sensor. After cleaning, test the watch on a walk or run to see if the elevation data returns.
2. Check Activity Settings
Go to your activity profile on the watch:
- Select your activity (Run, Bike, Hike, etc.)
- Go to Settings > Data Screens > Elevation
- Ensure Elevation is enabled and visible
If it’s missing, add it back to your data screens.
3. Update Your Firmware
Connect your Forerunner 935 to Garmin Express on your computer or use the Garmin Connect Mobile app. Check for updates and install the latest version. Updates often include sensor fixes and better data processing.
4. Calibrate The Altimeter
You can calibrate the altimeter using known elevation (e.g., from a signpost or online map) or let it auto-calibrate with GPS:
- Go to Settings > Sensors > Altimeter > Calibration
- Choose GPS or Manual, and follow the instructions
This gives your watch a correct starting elevation, so future data is accurate.
5. Reset The Device
If all else fails, try a soft reset:
- Hold the Light button until the device powers off, then restart.
Or, perform a factory reset (be sure to back up your data):
- Go to Settings > System > Reset > Delete Data and Reset Settings
This clears temporary glitches and returns settings to default.
6. Test In A Different Environment
Some users find that the watch works well outdoors but fails indoors or near metal structures. Test your device in an open area, away from buildings, to see if the problem continues.
Comparing Elevation Recording With Other Devices
Here’s how the Forerunner 935 stacks up against similar watches for elevation accuracy:
| Device | Elevation Sensor | Accuracy (± meters) | Common Problems |
|---|---|---|---|
| Garmin Forerunner 935 | Barometric Altimeter | 3–5 m | Blocked port, calibration errors |
| Garmin Fenix 5 | Barometric Altimeter | 2–4 m | Blocked port, sensor drift |
| Apple Watch Series 6 | GPS + Barometric | 5–10 m | GPS drift, recalibration needed |
| Suunto 9 | Barometric Altimeter | 3–5 m | Sensor clog, firmware issues |
As you can see, barometric altimeters are generally more accurate, but they need proper maintenance and calibration.
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Preventing Future Elevation Recording Issues
- Clean the watch after runs, especially if exposed to dirt, sweat, or water.
- Check software updates monthly. Most bugs are fixed by new firmware.
- Calibrate the altimeter regularly, especially when changing locations or after a flight.
- Avoid exposing the watch to strong impacts or submerging it in water for long periods.
- Keep activity profiles simple. Complex settings can sometimes cause bugs.
Many users don’t realize that sweat buildup can block the barometric port over time—even if you never run in mud. Also, changes in local weather (like sudden pressure drops) can affect short-term readings, so always calibrate if you notice strange data.
Real-world Example
Sarah, an ultramarathon runner, noticed her Garmin Forerunner 935 stopped showing elevation gain after a muddy trail race. She tried syncing and resetting, but nothing worked. After reading Garmin forums, she cleaned the barometric port with a soft brush—and her next run showed correct elevation data. This simple fix solved weeks of frustration.
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When To Seek Professional Help
If your watch never records elevation, even after cleaning, updating, and resetting, the barometer may be damaged. This requires professional repair. Garmin support can run diagnostics and may replace the sensor under warranty if your device is still covered. Attempting to repair the sensor yourself is risky and can void your warranty.
Elevation Data And Third-party Apps
Some users sync activities to Strava, TrainingPeaks, or other platforms. If your watch records no elevation, these apps usually cannot add accurate elevation data after the fact. Some platforms “guess” elevation using GPS track data, but this is often less accurate and can show strange graphs. Always try to record correct elevation at the source—the watch.
Elevation Recording: Key Data Points
Here are a few quick stats about elevation recording on the Garmin Forerunner 935:
| Condition | Expected Elevation Accuracy | How to Improve |
|---|---|---|
| Clean Barometric Port | 3–5 meters | Clean after every 5–10 workouts |
| Manual Calibration | 2–3 meters (if done correctly) | Use known altitude reference |
| Outdated Firmware | Up to 20 meters off | Update firmware regularly |
| Blocked Port | No data or flatline | Clean with soft brush or air |
Pro Tips And Insights Most Beginners Miss
- Altitude drift is normal: Even with a clean port, your watch may show slight changes in elevation while standing still. This is due to weather and pressure changes. It’s not a sign of a broken sensor.
- Auto-calibration isn’t perfect: If you let the watch auto-calibrate using GPS, it’s less accurate than using a known location. Whenever possible, calibrate at a place where you know the real elevation.
- Elevation is not instant: When you start an activity, the watch may take a few minutes to stabilize elevation readings. Don’t worry if the numbers look odd at first.
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Frequently Asked Questions
Why Is My Garmin Forerunner 935 Showing Flat Elevation Graphs?
A flat graph usually means the barometric port is blocked or the sensor is not working. Clean the port and recalibrate. If the problem continues, check for firmware updates or possible hardware damage.
How Often Should I Calibrate My Altimeter?
For best results, calibrate before important workouts or races, especially if you change locations, travel, or notice strange data. Manual calibration using a known elevation is most accurate.
Can Sweat Or Water Permanently Damage The Barometric Sensor?
Occasional sweat or water usually won’t damage the sensor if you clean the port regularly. However, prolonged exposure or not cleaning can lead to corrosion or blockage, causing long-term issues.
Is Gps-based Elevation Less Accurate Than The Barometric Altimeter?
Yes. GPS-based elevation can be off by 10–50 meters, especially in areas with poor signal. The Forerunner 935’s barometric altimeter is usually accurate within 3–5 meters when clean and calibrated.
Where Can I Find Official Support For This Issue?
For detailed troubleshooting and warranty service, visit the official Garmin Support page.
If your Garmin Forerunner 935 isn’t recording elevation, don’t panic. Most problems are easy to fix with cleaning, calibration, or a software update. Understanding how the barometric sensor works and how to care for it will help you get the most from your device. Consistent maintenance means you’ll always have accurate elevation data to analyze, share, and celebrate your achievements.