Garmin Descent Error Code 20: How to Fix It

Q: What is Error Code 20 on the Garmin Descent?

Error Code 20 on the Garmin Descent is an ascent rate warning. It activates when the device detects that you are ascending through the water faster than the safe threshold — typically 9–10 meters (30 feet) per minute. This is a critical safety alert to help prevent decompression sickness.

Q: Is Error Code 20 dangerous on the Garmin Descent?

The warning itself is not dangerous — it is a protective alert. However, the situation causing the warning (ascending too fast) is potentially life-threatening. Ascending too quickly can cause decompression sickness or arterial gas embolism. You must slow down immediately when this warning appears and follow all instructions on your device.

Q: Can I turn off the ascent rate warning on my Garmin Descent?

You can adjust alert settings in your Garmin Descent's dive settings menu, but it is strongly inadvisable to disable or raise the ascent rate alert threshold beyond the manufacturer's recommended value. This warning exists to protect your life. Consult your device manual and a certified dive professional before changing any safety alert settings.

Q: How do I reset the Garmin Descent after an ascent rate warning?

There is no specific reset needed for Error Code 20 — the warning will clear automatically once you slow your ascent to within safe limits and complete any required safety stops. After the dive, sync your device with the Garmin Connect app to review your dive profile and ensure everything is logged correctly.

Q: Why does my Garmin Descent keep showing Error Code 20 even when I ascend slowly?

If the ascent rate warning triggers repeatedly when you believe your speed is within safe limits, the pressure sensor on your Garmin Descent may be contaminated with salt, debris, or corrosion, or there may be a firmware issue. Rinse the device in fresh water, check for firmware updates via Garmin Express, and verify your ascent rate alert threshold in settings. If the problem continues, contact Garmin support or an authorized service center for a sensor inspection.

Abstract

Garmin Descent Error Code 20 is an ascent rate warning that triggers when you are rising through the water column faster than the safe threshold recommended by your dive computer — typically faster than 9–10 meters (30 feet) per minute. This warning is a critical safety alert designed to help prevent decompression sickness (DCS), also known as 'the bends,' which can occur when dissolved nitrogen comes out of solution in your tissues too rapidly. If you see this warning underwater, you must slow your ascent immediately and follow your computer's guidance before continuing to the surface.