Why does not go out the screen when talking on Xiaomi Mi 9T: a full analysis of the problem

The problem of Xiaomi Mi 9T screens not going out during a phone call is more common than it seems, and users face it both after updating the firmware and for no apparent reason, it seems like a trifle — but in practice it is annoying: random taps interrupt the call, the battery goes down faster, and it is simply inconvenient to talk to the display on.

In this article, we’ll look at all the possible causes, from trivial proximity sensor settings to hardware malfunctions, how to diagnose a problem yourself, which parameters to check first, and when to bring your phone to service, and unique life hacks that are rarely found in standard instructions (for example, how to get around a problem with ADB if the sensor refuses to work correctly).

Let's warn you right away, 80 percent of the time, it's software or settings that are wrong, but there are more serious scenarios, like the incoming sensor plume being damaged after the phone falls, and we can help you determine what's causing the failure and what to do in each case.

For convenience, we divided the solutions into two groups:

1. Quick fixes (take 1-5 minutes).
2. Deep diagnosis (will require more time or contact the service).

If you are not sure of your technical skills, don’t take risks with disassembling your phone. Some manipulations (such as cleaning the sensor with alcohol) can make the problem worse if done incorrectly.

1. Checking the proximity sensor: why it doesn't work

The proximity sensor is a little sensor next to the front camera that detects when you're holding your phone to your ear, and if it breaks down or gets dirty, the Mi 9T screen stops going out when you call. Here's how to check it:

First, make sure that the sensor is not covered by a film or a cover. Even a thin protective film can block the infrared signal. Try making a call without a cover - if the screen is out, the problem is solved.

If the case is not, but the sensor still does not work, use the secret engineering menu:

1. Open the Phone app.
2. Enter the combination: ##6484## (some firmware may not work, then use an alternative method).
3. Select Proximity Sensor (approximation sensor).
4. Put your hand to the top of the screen, and the value should change from 5.00 to 0.00.

If the numbers don't change, the sensor is faulty or contaminated, and then cleaning (more on that below) or replacing will help.

2. phone settings: what could have gone wrong

Sometimes the problem is that you've lost your settings, like when you update MIUI, you reset some settings to default values, and here's what you need to check first:

Disable the screen is always on (AOD):

1. Go to Settings → Display.
2. Find the screen always on (or Ambient Display).
3. Turn it off or set the timer to a minimum.

Checking the proximity sensor settings:

1. Go to Settings → Additional → Special Opportunities.
2. Find the proximity sensor and make sure it's on.
3. If you have the option Calibration sensor – execute it.

It's also worth checking if left-handed mode is activated in the call settings, and sometimes it interferes with the sensor's performance.

Turn off AOD (Always On Display)| Check the proximity sensor in the engineering menu | Calibrate the sensor | Turn off left-handed mode in the call settings | Make sure there are no MIUI-->

3. Software failures: how to fix without resetting

If the sensor is working, but the screen is still not going out, it could be an application conflict or a system services failure.

Reboot your phone. It's banal, but it often helps. Hold the power button for 10 seconds until the phone turns off, then turn it on again.

Cleaning the cache of system applications:

1. Go to Settings → Applications → Application Management.
2. Find the phone and contacts, open them in turn.
3. Press Warehouse. → Clear the cache.

If that doesn’t help, try disabling battery optimization for the Phone app:

1. Go to Settings → Battery and Performance → Battery Optimization.
2. Find the phone in the list and select No Limits.

Important: If the problem occurred after the MIUI update, try to roll back to the previous firmware version. Sometimes new builds contain bugs related to the operation of the sensors.

4. Hardware malfunctions: when cleaning or repair is needed

If all the software methods have been tried, but the Mi 9T screen still doesn't go out when you talk, it's probably hardware.

The proximity sensor gets contaminated, and over time, the sensor's opening gets dust, sweat, or residue of adhesive from the film, to clean it up.

1. Turn off the phone.
2. Take a toothpick or cotton swab dipped in isopropyl alcohol (do not use water!).
3. Carefully clean the area around the sensor (usually it is located to the left of the speaker).
4. Let the phone dry for 10-15 minutes before turning on.

Sensor plume damage, and if the phone fell or was mechanically loaded, the plume connecting the sensor to the motherboard could be damaged, and the screen would not go out under any circumstances, and the solution is to replace the plume in the service center.

The sensor itself is malfunctioning. It's rare, but it happens that the sensor fails for no apparent reason, and you can only diagnose this by replacing it with a known working one.

If you are not sure about your phone disassembly skills, it is better to contact the service.The cost of replacing the sensor or plume in the Mi 9T usually does not exceed 1,500-2,500 rubles (2026).

5. Alternative solutions: if nothing helps

If you've tried everything, but the screen still doesn't go out, you have to take radical measures.

Using apps to force the screen to shut down. Google Play has utilities like Proximity Sensor Fix or Screen Off and Lock that allow you to manually control the screen while you call, minus — they require additional permissions and can conflict with MIUI.

Disabling the proximity sensor via ADB. If the sensor is faulty, but you need to urgently resolve the problem, you can turn off its verification:

adb shell settings put system proximity_delay 0

This command will make the screen go out 0 seconds after the call starts.

adb shell settings put system proximity_delay 250

Factory reset. Extreme measure, but sometimes helps. Back up your data before reset!

1. Go to Settings → About the phone → Reset settings.
2. Choose to erase all data.
3. Confirm the action.

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If you often experience sensor issues on Xiaomi, install the Sensor Test app from Google Play.It shows the status of all sensors in real time and helps you quickly diagnose faults.

6. Frequent user errors: what not to do

When trying to fix a screen problem, many people make mistakes that only make things worse, and this is something that is strongly discouraged:

❌ Use sharp objects to clean the sensor. Needles, knives or metal toothpicks can scratch the glass or damage the sensor itself.

❌ Install unofficial firmware in hopes of fixing bugs. ROM They often break down the sensors even more.

❌ Disassemble the phone without experience. 9T fragile plume of the display - it is easy to break with a careless opening.

❌ Ignore updates MIUI. Sometimes sensor bugs get fixed in new firmware versions, and if you skip updates, you run the risk of being left with an unresolved problem.

❌ Using a phone with wet hands, moisture can get into the sensor hole and cause contacts to corrosion.

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If you clean the sensor or reset the problem, and then it comes back, it's probably because of physical wear, and then you can only change the sensor or the plume.

7. Comparison of decision methods: what works best

To make it easier for you to choose the right method, we have compiled a table with the pros and cons of each method:

As you can see from the table, cleaning the sensor and resetting the settings provide the best balance between efficiency and risk, and if the problem is hardware, you can't do without a visit to the service.

FAQ: Answers to Frequent Questions