Restoring Heart Rate Sensor on Xiaomi Mi Band 8

Heart rate sensors are the pulse that keeps a fitness tracker in sync with your body’s rhythm. When the sensor stops reading accurately, the data you rely on for workouts, sleep analysis, and overall health monitoring becomes unreliable. Restoring the sensor on a Xiaomi Mi Band 8 can be a straightforward fix if you follow the right steps, or it may reveal a deeper hardware issue. This guide walks you through every possible solution—from simple software tweaks to physical cleaning—so you can get your Mi Band 8 back to a full‑functioning heart‑rate monitor.

Why the Heart Rate Sensor Might Fail

The Mi Band 8 uses optical photoplethysmography (PPG) to detect blood flow through your wrist. This technology is highly sensitive to a handful of common problems:

• Dirty or obstructed sensor surface – Sweat, oils, and skin debris can interfere with light reflection.
• Loose or damaged sensor connection – Manufacturing tolerances, drops, or pressure can loosen the internal contacts.
• Battery drain – A low voltage can limit the light intensity and data‑processing power.
• Firmware glitches – Bugs in the firmware or corrupted data can disrupt the heart‑rate algorithm.
• Physical damage – Water exposure, impact, or pressure may crack the sensor chip or its protective layers.

If you notice irregular heart‑rate readings, missing heart‑rate data, or a “not detected” message in the Mi Fit app, one of these factors may be at play.

Symptoms That Indicate a Sensor Problem

Recognizing early signs is key to preventing more extensive damage. Pay attention to these warning signals:

• Inconsistent readings – Heart‑rate values jump wildly or do not change with activity.
• Missing data – Long gaps in the heart‑rate timeline, even during active periods.
• App warnings – The Mi Fit app displays “Heart rate sensor error” or similar alerts.
• Physical changes – The sensor window looks discolored, cracked, or covered in grime.
• Battery drain – The band’s battery life drops significantly after a firmware update.

If any of these symptoms appear, start with a simple reset before moving on to more invasive troubleshooting.

Pre‑Check: Basic Troubleshooting Steps

Before diving into firmware or hardware solutions, perform these quick checks:

1. Restart the Band – Turn the Mi Band 8 off and back on. A fresh start can clear temporary glitches.
2. Re‑pair the Device – Unpair the band in the Mi Fit app, then re‑pair it. This forces a new connection handshake.
3. Check Band Position – Make sure the band sits snugly but not too tight; an improper fit can cause poor contact.
4. Verify Battery Level – Charge the band to at least 50 % and keep it on the charger for an hour to ensure stable power.

If the heart‑rate sensor still misbehaves after these steps, proceed to the more detailed fixes below.

Updating Firmware and App

Out‑of‑date software is a common culprit behind sensor misreading.

• Mi Fit App – Open the app, tap your profile, and look for “Device updates.” If an update is available, install it.
• Band Firmware – Firmware updates are delivered through the app. After updating the app, the band should automatically pull the latest firmware when connected to Wi‑Fi or a stable network.

Tip: After an update, wait 10–15 minutes before starting a new workout. The band recalibrates its sensors during this window.

Battery Health and Voltage Checks

A weak battery can reduce the LED intensity needed for accurate PPG detection. While the Mi Band 8 does not expose battery voltage to the user, you can infer its health:

• Battery Life Trend – If you notice the battery draining faster than usual, consider replacing it. Xiaomi does not officially support battery replacement, but some third‑party repair shops offer this service.
• Charging Time – If the band takes significantly longer to reach full charge, the battery may be aging.

If the battery appears degraded, a replacement can restore sensor performance by ensuring consistent power delivery.

Cleaning the Sensor Surface

This is often the most effective and simplest fix.

1. Turn off the Band – Ensure no data is being recorded during cleaning.
2. Use a Soft, Dry Cloth – A microfiber cloth works best.
3. Gentle Wiping – Lightly wipe the sensor area (the back of the band where the light sits). Avoid applying pressure.
4. Avoid Liquids – Do not use water or cleaning sprays; they can seep into the band and damage internal components.

If you suspect significant grime or oil, use a cotton swab lightly dampened with isopropyl alcohol (70 %) and wipe gently. Dry the area thoroughly before turning the band back on.

After cleaning, power on the band and run a heart‑rate test. The readings should stabilize if the issue was due to debris.

Re‑Calibration of the Heart Rate Algorithm

Sometimes the sensor hardware is fine, but the calibration parameters are misaligned.

1. Open Mi Fit – Navigate to the heart‑rate settings.
2. Select “Calibrate” – The app will guide you through a short calibration routine.
3. Follow On‑Screen Prompts – Keep the band still and steady while the app takes a few seconds of data.
4. Complete the Process – Once finished, the app will store the new calibration values.

This procedure is especially helpful after a major firmware update or if you notice irregular data after a software change.

Resetting Sensor Settings Without a Full Factory Reset

If you suspect the sensor settings themselves are corrupted, resetting them may help:

1. Go to Settings → Sensors – In Mi Fit, find the sensor configuration page.
2. Tap “Reset” – Confirm when prompted. This action restores sensor defaults but preserves other app data.
3. Restart the Band – Power off and on again.

This reset can resolve conflicts between the sensor and other health tracking features (e.g., sleep mode, heart‑rate zones).

Factory Reset as a Last Resort

A factory reset wipes all data from the band, returning it to its original state. Use this only if all other steps fail.

1. Open Mi Fit – Go to Settings.
2. Select “Reset” – Confirm the choice. The app will initiate the reset.
3. Re‑pair the Band – After the band reboots, pair it again with your phone.

Warning: You will lose all stored data, so back up any important information beforehand.

Using the Mi Fit App for Advanced Diagnostics

The Mi Fit app offers diagnostic tools that can reveal deeper sensor issues.

• Battery Health Report – Provides details on battery usage and health.
• Sensor Calibration Log – Shows past calibration attempts and success rates.
• Firmware Version History – Helps identify whether recent updates introduced bugs.

If the diagnostic logs consistently report sensor errors, you may need to seek professional repair or consider a replacement.

When Physical Repair Is Needed

If the sensor is physically damaged—cracked, discolored, or completely non‑responsive—the internal optics may need repair. Xiaomi does not officially support user-level repairs for the Mi Band 8, but several third‑party services specialize in band repairs:

• Screen and Sensor Replacement – Professional technicians can swap out the sensor module.
• Component Re‑Soldering – In rare cases, a mis‑soldered sensor can be re‑connected.
• Case Replacement – A damaged protective case may expose the sensor to the environment.

Choose a reputable repair shop that offers a warranty on their work. Keep in mind that opening the band yourself voids any remaining warranty.

Preventive Maintenance Tips

Regular upkeep can prevent most heart‑rate sensor failures:

• Clean Regularly – Wipe the sensor once a week, especially if you sweat a lot.
• Avoid Extreme Conditions – Keep the band out of hot water, steam rooms, and direct sunlight for extended periods.
• Charge Consistently – Maintain the battery above 20 % to avoid voltage drops.
• Update Software Promptly – Install firmware and app updates as soon as they appear.

By integrating these habits, you’ll extend the life of your Mi Band 8’s heart‑rate sensor and preserve the accuracy of your health data.

Frequently Asked Questions

Q: Does a battery replacement fix heart‑rate sensor issues?
A: If the battery is weak, it can reduce sensor performance. Replacing the battery restores consistent power, but if the sensor hardware is damaged, the issue will persist.

Q: Can I manually replace the sensor myself?
A: The sensor is integrated into the band’s PCB. DIY replacement is not recommended and will likely damage the device.

Q: How long does a calibration routine take?
A: The calibration process takes less than a minute. You simply stay still while the app records a short burst of heart‑rate data.

Q: My heart‑rate data is still wrong after all these steps. What now?
A: Contact Xiaomi support or a certified repair center. The sensor may be defective, requiring professional service or a replacement unit.

Final Thoughts

The Mi Band 8’s heart‑rate sensor is a critical component for accurate fitness tracking. By systematically diagnosing the problem—starting with software updates, cleaning, and recalibration—you can often restore the sensor’s function without professional help. If the issue persists, consider hardware repair or replacement. Regular preventive care will keep the sensor working smoothly for months or even years. With the right attention, your Mi Band 8 can continue to be a reliable companion on your fitness journey.