If you have a Fitbit Sense smartwatch, one of its key features may not be working properly. But don't worry - Fitbit is here to help.

On Fitbit's community forum, several users have stated that they have received an email from the company alerting them about the Fitbit Sense. According to the email, Fitbit has confirmed that "there is a hardware issue with your device that may prevent it from working properly. The company is asking those affected to send in their watches for a free replacement.

Specifically, the problem appears to be with the Fitbit Sense ECG app reading ECGs; Fitbit confirmed the issue to The Verge, adding that the problem is limited to a small number of devices (about 900 worldwide).

Still, the ability to perform ECG readings is a big deal for Fitbit Sense, making the $329 smartwatch sit out of many other Fitbit products. The Sense also includes features that are only available on devices like the Apple Watch 6 and Samsung Galaxy Watch 3.

If you launch the ECG app on the Fitbit Sense and place your thumb and index finger on either corner of the watch, the app will tell you if you have an irregular heartbeat. This is not a substitute for a formal diagnosis, but it is an effective early warning to seek medical attention.

The problem that occurred with some Fitbit Sense models was that the app incorrectly determined the results to be "inconclusive," which is certainly worrisome for people with regular heartbeats and potentially dangerous for those who actually suffer from atrial fibrillation.

After this article first appeared last week, Fitbit commented:

"A very limited subset of initial Fitbit Sense shipments (a few hundred units worldwide) will have the ECG app default to "Inconclusive" while reading We have found an issue that may cause the ECG app to display "Inconclusive" by default while taking a reading. We were able to identify the affected devices during setup and immediately contacted these users and provided them with a new replacement device free of charge. No other Fitbit devices are affected and no future Sense devices shipped will be affected by this issue."

Fitbit appears to have been able to contact affected Fitbit users directly, so even if you don't hear from the company, your Fitbit Sense will be fine.If you experience any problems with your Fitbit Sense, or if Fitbit has contact you about replacing your smartwatch, please let us know in our forums.