Forerunner 235 - HR readings completely wrong after 5.30/5.40 update

The same problem

Got this device some 7 or 8 weeks ago (I think the version was 4.70 at that point). The HR readings were pretty good (with some spikes and/or inaccuracies). I was satisfied. However 2 weeks (or so) ago after upgrading to 5.3 I started to have major issues (things are still same now after upgrading to 5.40).

There are two major problems:
1. The HR readings during workouts are completely wrong. The device reads something in 85 - 95 bmp range 90% of the time with occasional periods of good and realistic readings that are however short and do not account for more than 10$ of the workout.
2. If I remove the watches from my wrist (like during night), the HR reading won't start at all until I restart the device (this is hapenning 100% of the time while it was not happening at all before the update).

Here is sample run from before the update. It says version was 4.70. The HR readings seem to be quite good: https://connect.garmin.com/modern/activity/1298881922
Here is sample run after the update. It says version was 5.40. The HR reading are completely wrong 90% of the time: https://connect.garmin.com/modern/activity/1309337404

Any ideas what's wrong and how to resolve this.

Any input is greatly appreciated.

NOTE: I have tried to reset the device and restarted it numerous times.

Hi.
I have tse same problem. Is it posible return to a previous versión?

Yeah I'm having the same issue, HR rate seemed unusually low given I was running at a fast pace, my HR never went above 130.
The past two runs I've been on have been more realistic though so I'm unsure if you maybe just need to give it a few runs to calibrate or something.
Hopefully yours will even out soon:)

You guys are seeing the "Wrist HR Ready" display before starting the run?

I've noticed sometimes on lifting workouts that if i don't wait.... it will display/record a heart rate... and will have a heck of a time locking onto my heart rate while doing a workout. Until I sit still for a while, then its fine for the rest of the workout - the contractions of muscles and constantly changing HR give the averaging/filtering calculation a heck of a time I imagine.

Otherwise my wife and I have both had pretty solid data using 5.4 (for me mostly walking/lifting), wife's had been solid running.

Yes, I get the "wrist HR ready". But generally it does not make any difference when I wait for it or don't. During the run, the reading can be fine for let's say 5 minutes in a middle of an hour long run and it gets lost again.

Got the same issue after 5.20/5.40 update. Instead of the usual 150-160 range, it shows 120-130 most of the time, occasionally picking the right HR, but then going crazy again. For sprints it used to pick up the 170-180 range like 30-40 seconds behind the real increase, now it never picks up the elevated HR.
A ticket to Garmin where I specifically asked them not to tell me to update to the latest version, which they do by default got the usual response - update to the latest version :)

By the way, changing the data recording frequency from "Smart" to "Every second" alleviated the issue very slightly, managed to clock a couple of runs with good HR readings, but then had a few with completely messed up numbers.

Got the same issue after 5.20/5.40 update. Instead of the usual 150-160 range, it shows 120-130 most of the time, occasionally picking the right HR, but then going crazy again. For sprints it used to pick up the 170-180 range like 30-40 seconds behind the real increase, now it never picks up the elevated HR.
A ticket to Garmin where I specifically asked them not to tell me to update to the latest version, which they do by default got the usual response - update to the latest version :)

By the way, changing the data recording frequency from "Smart" to "Every second" alleviated the issue very slightly, managed to clock a couple of runs with good HR readings, but then had a few with completely messed up numbers.

Thanks for this tip dzhedaj. I'll try the run I plan for tomorrow with the "Every second" setting to see if it makes any difference.

Same here. Worthless.

The main reason I use this watch is for heart rate training. The readings are so far off that my Garmin 235 is now just a very expensive watch.

Heres my first post. After 5,000 km with TomTom Runner and Chest strap I've moved to Garmin.

First impression after a mere few days and 30 km's under my belt I'm happy withe the HRM. It doesn't spike in the first 5km like tomTom did (had me at 220bpm - Garmin has me at 145) nor during the runs.

As I sit here the 235 has my hr at 60 and using the HRM on my Samsung s5 I end up with 60bpm as well.

So far no issues with HRM. Early days I know and I have a trail half marathon on Sunday so I'l use the 235 on Tom Tom for a further comparison

Tried to change the settings to "every second" but that did not have any impact. Today's run had the watch sitting between 85 and 95 bpm for 59 minutes and only twice for about 1 minute it started to read reasonable values around 140 bpm.

Oh well, I just wonder why it used to work just fine with 4.70.

The completely wrong bpm makes the recovery time and kcal counts completely off as well.

First, I've noticed the Wrist Heart Rate monitor will read low if you have the strap too loose. Yeah, you really do need to have the watchband a bit snug to get accurate readings. This particular issue will only be emphasized if you are doing something with a lot of arm movement like running. Before I purchased my 235 I was made aware of this issue during research on the 235 and before buying the watch I had the shop get confirmation that the chest monitor I used with my Forerunner 15 would also work with the 235 and it will. In fact if you are wearing a chest monitor that is the default device for the Heart Rate tracking. About the only time it will "drop out" with the chest monitor in place is if the battery in the monitor is getting week, something that happened to me today. When I held the watch near the chest monitor it used that for heart rate, however at arms length it was changing to the wrist monitor.

Conclusions. I would recommend getting the Chest Monitor if you are doing any running. I would also suggest that you also tighten up the wrist strap any time you engage in an activity where you want accurate heart rate data where you won't be using a chest monitor. I'll also say that if you find your wrist getting sweaty and wiggle the strap a bit to ease the discomfort you should expect a "break" in the heart rate tracking data. These are optical sensors and in order to work well they need to be as movement free as is possible, so keep that in mind any time you see reading that seem a bit flaky.