Garmin Forerunner 235 Heart Rate Monitor Not Working – How to Fix?

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The forerunner 235 heart rate monitors are fickle monsters that sometimes do not work rightly. The Garmin Forerunner 235 incorporates an optical heart rate sensor incorporated into the wrist, making the heart rate measurements more reliable and comfortable than a chest strap. The testing reveals that Garmin 235’s wrist-based heart rate values are frequently off by 10-30 beats per minute, making it useless for tracking the runs.

An optical HR sensor measures changes in minutes as it reflects light from the veins of your wrist during each pulse. The measurement is not short as electrical measures taken using a chest strap, and other shifting light sources can throw it off, but its convenience should more than compensate for those flaws. We will look at different Garmin forerunner problems and how to troubleshoot them in this article.

Table of Contents

Garmin forerunner 235 heart rate monitor not working

1. My Garmin forerunner 235 heart rate monitor not turning on or responding

If your Garmin fitness device is not turning on, you can conduct some basic troubleshooting steps to get back on the road. The following are the things that you should check and troubleshoot.

Is the device’s battery completely charged?  Use the power/data cable to connect the gadget to a power source. When charging the Garmin fore running 235 heart rate monitor, ensure that you consider the proper charging methods.

Is the charging wire in good functioning order? Verify that the cable is not damaged in any way that might prevent the device from working. Check the charging pins for debris and make sure they’re not bent. If required, replace the cord.

Is the device locked up or frozen?  In some instances, a device can lock up and not respond to any input, including pressing a key, swiping the screen, or plugging the device into external power. In this case, you can attempt to recover the device by performing the following steps.

NOTE: Following these steps may result in a loss of some data, such as recent steps taken (Activity trackers) or a loss of current time. To correct the time, sync the device with a smartphone using the Garmin Connect App or a personal computer using Garmin Express. For GPS devices, go outside and acquire a GPS signal. Plug the device into an external power source using the power/data cable. Press and hold the power key for about 15-20 seconds.

2. My Garmin device is paired; however, it is not connecting to my Garmin Connect account to sync data

Can not Sync gramin heart rate Data

If data from your Garmin device is no longer syncing to your Garmin Connect account, there are a few things you may do. There are certain troubleshooting procedures you may do that should help you solve your problem.

Steps to Troubleshoot:

NOTE: Make sure your Garmin device is within the Bluetooth range of your smartphone and that your smartphone is in the Bluetooth range of your Garmin device. Your device’s Bluetooth setting is not switched off. Either of these conditions will lead to your demise.

The Garmin Connect App on your smartphone is not syncing with your Garmin device.

Try each step, then check to see if the issue has been resolved:

  1. Turn your smartphone’s Bluetooth off and then back on.
  2. Exit the Garmin Connect application. After that, reopen it.
  3. Ensure that you turn off the Garmin gadget and then turn it back on. Devices that can be recharged but do not have a power button: Connect your gadget to a USB power source. If you’re using a Vivo fit device, skip this step because you won’t be able to power cycle it.
  4. Turn off the phone and then turn it back on.
  5. Open the Garmin Connect App and remove, then re-add the Garmin device.

A Lithium-Ion Battery in a Rechargeable Fitness Device’s Life Expectancy

Rechargeable Fitness Device

Charge/discharge cycling causes rechargeable Lithium-ion (Li-ion) batteries to lose capacity over time. All Li-ion batteries used in Garmin devices are replaced. The batteries in the Forerunner and Edge operate normally under normal situations.

After a few years of constant use, gadgets should have about 80% of their initial capacity. The regular loss of battery capacity can be accelerated by several reasons that include:

  1. High-temperature exposure is one of the most dangerous things you can do to your body.
  2. Leaving the battery charged or depleted for an extended period

When keeping the device for an extended period, it is recommended that it be partially charged (about 30 to 50 percent) and kept in a cold, dry location. Before an accurate measurement of battery capacity can be made, some devices may require a full charge and discharge cycle.

On a Forerunner 235, turn on Bluetooth pairing mode

If you want to use the Garmin Connect app to connect a Forerunner 235 to a smartphone, you must first enable Bluetooth pairing on the device. When pairing mode is enabled, the Garmin Connect app will look for a Bluetooth beacon signal. The following are the steps to enable Pairing mode:

NOTE: The next instructions are accessed through the Settings menu, not the Controls menu.

To enable pairing mode on a Forerunner 235, follow these steps:

  1. On the watch, press the button on the top right side.
  2. Select the menu by pressing the button at the bottom left.
  3. Select Settings from the drop-down menu.
  4. Select Bluetooth by scrolling down.
  5. Pair Your Mobile Device
  6. The Forerunner 235 will now be able to connect to Bluetooth devices.

On a Garmin device, you may control what Android Smart Notifications appear

Managing which Android phone notifications are sent to a Garmin gadget might be difficult. The Garmin Connect app’s settings are used to operate the device. To manage Smart Notifications, follow these steps:

  1. Open the Garmin Connect app and choose (upper left-hand corner)
  2. Choose a setting
  3. Select Smart Notifications from the drop-down menu.
  4. Toggle to enable or disable all Smart Notifications or customize by picking from the options.

My watch’s heart rate sensor isn’t accurate

Heart Rate Sensor not Accurate

Optical heart rate sensors function by detecting minute variations in blood volume in the capillary layer just beneath the epidermis (the outermost of the three layers that make up the skin) as blood passes through the wrist. Garmin’s wrist heart rate monitor technology, on the other hand, although the technology is cutting-edge, there are inherent limits in the technology that may cause some heart rate readings to be erroneous in certain situations.

The following material explains the most common factors that can impair heart rate accuracy and enhance it.

Wearing the Watch Incorrectly

Ensure the following for the optimum heart rate performance from your watch. At all times, the optical heart rate sensor must be in contact with your skin. The watch is worn snugly, but not excessively so.

If the watch is worn too loosely, it can move about, causing a gap between the optical heart and the rest of the watch. If the watch is worn too tightly, blood flow may be restricted. When you can move the watch, and the skin beneath it moves with it, the watch is correctly tight.

Heart rate performance can be affected by certain activities

Activities that cause the wrist to flex (for example, rowing, weight lifting, or clutching a tennis racket) can have the same effect as wearing a watch too tight and impede blood flow. If this happens, the watch may have trouble detecting an accurate heart rate.

The accuracy of heart rate can be affected by tattoos

Tattoos can affect the accuracy and effectiveness of heart rate sensors. The optical sensor may not even turn on in some circumstances. Some tattoos can obscure light because of their ink, pattern, and saturation. It may be difficult to get a good heart rate reading if the light does not reach the sensor. Garmin suggests that the watch be worn in a place where tattoos are not visible.


To conclude, the gamin force runner 235’s optical measures are generally under a few beats/minute of the measurements of the chest strap, mostly when running at a somewhat consistent exertion level.

It is important to troubleshoot the problems associated with the Garmin forerunner heart rate monitor for its proper working.

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