Why the Redmi 9’s proximity sensor is so important and where to look
The proximity sensor in Xiaomi Redmi 9 smartphones is a small but critical element that makes calls feel comfortable. It automatically turns off the screen when you hold your phone to your ear, preventing accidental taps and saving battery life. However, many users face a problem: the sensor starts to crash, the screen does not go out during a conversation or, conversely, does not turn back on. To understand the reason, you first need to know exactly where the proximity sensor on Redmi 9 is and how it works.
In this article, we will not only show it on the front panel, but also explain how to test the sensor without disassembling the phone, what applications to use to do this, and what to do if it ceases to function, and pay special attention to typical diagnostic errors — for example, why tests through the engineering menu can give false results, and how to get around it.
Where exactly is the proximity sensor in Xiaomi Redmi 9
In the Redmi 9 (M2003J15SC, M2003J15SS and other versions), the proximity sensor is integrated into the top of the screen, next to the front camera. Specifically, this is a small circular hole to the left of the selfie camera, when viewed at the phone in a standard position (the speaker on top), the photo below shows its exact location:
Photo of the proximity sensor location (clickable)
It's important to understand that this is not a separate module, but part of a sensor complex that also includes a light sensor, and in some cases, proximity problems can be related to neighboring elements, for example, if a protective glass or film overlaps the view.
If you're disassembling a phone, the sensor is soldered to the motherboard and connected to it through a flexible plume from the display module. The Redmi 9 uses an APDS-9960 infrared approach sensor or its analogue, which works on the basis of reflected light, which means that it needs a direct "overview" to work correctly - any obstacles (dust, dirt, cracks on glass) can cause malfunctions.
How to check the proximity sensor without disassembling the phone
Before you bring your phone to the service, try to diagnose the problem yourself. Here are 3 reliable ways to check the proximity sensor on Redmi 9:
- 📱 Testing through the engineering menu: Enter the code ##6484## in the phone application, then select Proximity Sensor. Cover the sensor with your hand - the value should change from 5 (far) to 0 (close).
- 🔍 Diagnostics: Install utilities like CPU-Z Phone Doctor Plus – This shows the status of all sensors, including the approximation.
- 📞 Practical test: Call someone and see if the screen goes out when you hold the phone to your ear.
Note that if the sensor in the engineering menu is responding to the hand, but the screen does not go out during the call, it may not be the hardware itself, but the firmware or settings, in which case resetting or flashing will help.
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If the sensor doesn't respond to any test, try cleaning the top of the screen with a soft wipe, sometimes blocking the infrared signal.
Typical malfunctions of the proximity sensor and their causes
The proximity sensor failures on Redmi 9 usually boil down to two scenarios: false positives (the screen goes out for no reason) or no response (the screen remains active during the call).
| Symptoms. | Possible cause | Decision |
|---|---|---|
| The screen doesn't go out when you ring. | Sensor contamination, plume damage, software failure | Cleaning, flashing, plume replacement. |
| The screen goes out arbitrarily | False positives due to protective glass or film | Plugging glass with a cutout for the sensor |
| Sensor's working in a second. | Poor plume contact or chip wear | Diagnostics in the service, replacement of the sensor |
| Tests show FAIL error | Hardware breakdown of the sensor or motherboard | Replacement of sensor or board repair |
The most common problem is with the safety glass, which many of the masters glue without a sensor cutout, which blocks the infrared signal, and if you've recently changed the glass and then you start to crash, this is the first candidate for testing.
How to calibrate the proximity sensor on Xiaomi Redmi 9
If the sensor is working but it doesn't work properly (e.g., the screen goes out too soon or later), it can be calibrated. In Redmi 9, it's done via an engineering menu:
- Open the Phone app and type ##6484##.
- Select Proximity Sensor.
- Press Calibrate (if the option is available).
- Follow the instructions on the screen – usually cover the sensor with your hand and hold it for a few seconds.
If there is no calibration point, try an alternative method:
- 🔧 Install Sensor Calibration from Google Play.
- 📊 Select the proximity sensor and start the automatic calibration.
- 🔄 Restart your phone after the procedure.
Calibration helps in ~60 percent of the time, if the problem is software, if nothing's changed, it's probably iron.
☑️ Checklist before sensor calibration
What to do if the proximity sensor does not work at all
If the sensor doesn't respond to any tests, and the calibration doesn't work, you'll have to take a more radical approach.
- Reset: Go to Settings → System → Reset and select Reset All Settings. This will delete user data, but often solves sensor problems.
- Flashing: Install the official firmware via the Mi Flash Tool (instructions are available on the 4PDA forums) This will help if the failure is caused by a software error.
- Contact cleaning: If you disassemble a phone, check the sensor plume on the motherboard – sometimes oxidation of contacts leads to a signal break.
- Sensor replacement: The service center can replace the sensor or the entire display module (if the problem is in the plume).
Important: In Redmi 9, the proximity sensor often fails after falls or moisture. If the phone falls, first check the integrity of the display plume - its cliff can simulate a sensor malfunction.
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If the sensor does not respond to calibration and tests, in 90% of cases, hardware failure is to blame - diagnostics are required in the service.
How to temporarily bypass the problem if the sensor is broken
If the proximity sensor does not work, and repair is postponed, you can temporarily adapt to the situation:
- 📵 Turn off the screen manually: During the call, press the power button to lock the screen.
- 🔄 Use a headset: Connect Bluetooth headphones or a wired headset - then no sensor is needed.
- 📲 Install an alternative dialer: Some applications (like True Phone) allow you to turn off the approach sensor response.
These methods don’t solve the problem, but make using the phone less annoying. Remember that constantly turning off the screen during calls increases the risk of accidental taps (for example, you can hang up the phone or turn on speakerphone).
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If you make frequent calls in the car, buy a magnetic holder for the phone – it will hold the Redmi 9 at eye level and the proximity sensor won’t get in the way.