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The Elevation Reading on My Forerunner 935 Is Wrong
The elevation reading you see comes from a barometric altimeter sensor inside the watch. This sensor detects barometric pressure changes in order to determine current elevation at a given point. If you believe the elevation reading from your watch is incorrect, there are a few troubleshooting steps that you can take to fix the problem.
Clean the Sensor Port on the Watch
A blocked or clogged sensor port can lead to:
Wrong elevation or barometer readings
Incorrect Floors Climbed credit
To clean the sensor, locate the port on the back of the watch (it will be a small hole at the 6 o'clock position). You can rinse the port with water or you can also soak the watch in water for 5 minutes, agitating it every minute to help breakdown and remove any debris, such as sweat crystals or skin cells. After cleaning and/or soaking, allow the watch to dry completely.
IMPORTANT: Do not insert anything into openings on the watch (including canned air) as this can damage the internal sensor.
Understand Contributing Factors That Can Affect the Sensor
There are additional factors that can contribute to an incorrect reading. These include:
An Incoming or Departing Low or High-Pressure System
This can cause your starting elevation reading to be too high or low. The elevation gain/loss is typically not affected by this.
A Windy Day
Wind can affect the sensor causing an inaccurate reading. If you are going to record an activity outdoors when it is windy we suggest wearing the sleeve of a shirt or coat over the watch.
Calibrate the Sensor
One other way to correct an elevation error is to calibrate the sensor. With proper calibration, the watch can achieve an accuracy of +/-50 feet at any given point. Use the information below to determine which calibration options are best for you.
Calibrating the Altimeter
Calibrating the altimeter should always be done outside with a clear view of the sky.
Hold Up to enter the Main Menu.
Select Settings.
Select Sensors & Accessories.
Select Altimeter.
Select an option:
Auto Cal. - When enabled this option will calibrate the altimeter anytime GPS is acquired.
Calibrate - This mode will allow you to calibrate the sensor using a current known elevation or the GPS elevation reading. Elevation calibrated through GPS is accurate to +/-400 feet at any given point.
From here you can choose Calibrate to calibrate the sensor using a current known elevation or by using the GPS elevation reading, or toggle the Auto Calibrate setting on or off.
I Continue to Have an Issue With Elevation Readings on My Watch
If you have followed all of the troubleshooting listed above and you continue to have an issue, you can request to have your watch replaced using the following tool:
Garmin's Online Exchange for the Forerunner 935
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IMPORTANT: The Garmin exchange tool is only available in select countries and an exchange fee may apply when submitting a request to replace your device. Refer to the drop-down list in the exchange link for details. Contact your local Garmin Product Support office for assistance if your country is not listed..