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Incorrect heartrate reading during activity

Hello,

I have purchased the Forerunner 45 to replace my Vivomove HR as I wanted to upgrade to more functionality and Body battery and GPS features.

My unit is working great however is showing an unexpected behavior.

- When I start the "Walking" activity with the Start/Stop button, the activity starts normally. I have setup the watch face during activity to show me distance under the current time, so there are 2 data lines shown (black font on a white background).

However, sometimes during activity, my watch displays a black-background screen, with a red heart icon, and showing "Heart Rate 255" (white font). Of course that's not true, 255 seems like a "default" reading.

Without doing anything, the screen then comes back to normal.

Do you notice this behavior too ?

When  I setup the activity watch face to display my heart rate, the reading is accurate and I have no issue.

Sorry for my english.

  • By different training unit, do you mean imperial instead of metric run goals? I have started using HRZ training, and my watch will read the correct heart rate, but I also get the 255bpm notification, even when I'm reading the HR monitor as much lower at that point in time. I'm manually tracking my heart rate during HRZ training, but would like to have the notifications set up properly!

  • I purchased a forerunner 45 last week and have exactly the same problem when doing a workout to heart rate zones. 

    Af first I thought it wanted me to try and get my pulse to 255!

    Any solutions? 

  • I'm having the same problems. So I noticed that it goes off several times during an activity, and I know my he is not 255. So I hit start>run>alerts>heartrate and all my zones are set to 255-255. I went into my device settings in the app and the heartrate zones there seem about right. I sync my phone and nothing happens. They still dont change. There is an option for reset but I don't know what that will do exactly. I have to look it up somehow. There is a custom setting, but I'd like to have my heartrate zones set based on my hr data. Plus I don't quite understand what it is asking. 

    • Please let me know when someone finds out! I would love to be able to see which heartrate zone I am in. I am wondering if when it beeps when I'm on a run, it hits the hr zones that are set on my phone. Bc one doesn't stay in one zone their whole workout. I dunno. Just wondering. 
  • My heartrate zones on the app are correct but on my phone under alerts when you select an activity, all my heartrate zones are 255-255. I have no idea how to change it. Someone else asked this question and someone figured out how to stop the 255 but I don't quite understand what they did.

  • I had the same issue and believe I have resolved it. Within Garmin Connect to to device settings, activity options and scroll down to "Options" select Walk and then you will see that the heart rate zone is selected by default with default heart rate zones for walking. You can then select your own zone or simply turn it off

  • I'm experiencing the same issue and have tried some of the measures mentioned below no changes. I wondered if there have been any success with rectifying the issue. Ive only had the watch for 3 weeks and the issue occurred and the 1st run and has been consistent since... Frustrating!  

  • My wife came back from her run with an exact same problem. Her FR45 would alert her of high HR and a glance at the watch would show 255. From what she reported the issue was really with the alert, not the actual sensor reading, so I went to alerts in the watch settings and it turned out her custom alert range (which I'd set up for her recently and which worked fine first time round) was showing 255-255. I changed it to what she wants it to be (127-137). She completed her run with no issues. 

    Later, I was able to figure out what happened.

    Unlike my FR245 on which settings are adjusted internally, the FR45 relies on Garmin Connect desktop app for most of its settings. To make things somewhat confusing, Garmin allows the user to overwrite those default settings on the watch but they will last only till the next sync when the app setting will default back. So what you need to do, always, is make sure that your HR slider alert is marked green in the app (my wife's wasn't and that was causing the problem) and digit set as you want it to be. Do not set alerts on FR45 itself unless you mean to use them only for a day, i.e. until the next sync. 

  • You are a savior. Thank you sir!

  • I have had the same issue since I bought mine last Summer. During a walk/hike the alert comes on and shows 255 which I would be dead, and during a run it shows 0. Once I save the activity on Garmin Connect it seems to show a fairly accurate heart rate during my activity. I have talked to a tech person they had me completely factory reset my watch and it still does it. It's very frustrating as the only reason I upgraded from my Vivoactive sport was for the heart rate monitor. I have my high and low alert zones set and they definitely are not set at 0 and 255. Lol Guess there is no fix for the issue.