Why it is important to know the year of release of Xiaomi Redmi 4X
Xiaomi Redmi 4X (codenamed santoni) remains popular even years after the official end of support, but its production date directly affects reliability, firmware compatibility and market value. For example, 2017 models have a different battery type (marked DM-06) than late 2018 batches – this is critical when replacing batteries.
Buyers of used phones often face fraud: sellers pass off old devices as “near new”, hiding the real age. and owners need to know the date of production to choose the right parts or understand why the device does not support the latest versions of MIUI. In this article, all working methods of verification, including little-known tricks with the engineering menu.
Note: The Redmi 4X was released from February 2017 to June 2018, but the date on the box and the actual build date may vary by 1-3 months.
Method 1: Serial number check (IMEI/SN)
The most reliable method is to decrypt the serial number (SN) or IMEI, and on the Redmi 4X, they are marked on:
- 📦 Box (barcoded sticker)
- 📱 Under the battery (if the back cover is removed)
- 🔢 In settings: Settings → The phone. → General information
Xiaomi serial number has a format XXXXXXXXXYYWW, where:
- YY is the last two digits of the year (e.g. 17 = 2017)
- WW – week of production (01 to 52)
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If the serial number starts with the letters L or M, it indicates production in 2017 for the Chinese market: European models are labeled K or N (2018).
An example of decryption:
| Serial number. | Year | A week. | Date of production |
|---|---|---|---|
| 8A7LN170345 | 2017 | 03 | January 2017 |
| 9B2KN182567 | 2018 | 25 | June 2018 |
| 7C1LM174890 | 2017 | 48 | November 2017 |
⚠️ Attention: On the fake Redmi 4X Serial numbers are often forged. mi.com/verify (It only works for official dealers).
Method 2: Production date by box and stickers
The original Xiaomi Redmi 4X box contains two key tags:
- The date of production on the sticker (YYYYY-MM-DD or YY/MM/DD) look for it on the white barcode label.
- Printing the batch at the bottom of the box (e.g. 17W25 = Week 25 of 2017).
Important: if the box looks new but the date is 2017 and the seller claims the 2019 phone is a clear sign of cheating.The Redmi 4X stopped releasing in mid-2018, so any later dates are fake.
How to distinguish the original box from a fake
Photos of examples of original and fake boxes:
Method 3: Check through the engineering menu (#4636##)
A hidden engineering menu allows you to find out the date of firmware assembly, which often coincides with the date of production of the device.
Open the phone app.
Enter the code ##4636##
Go to the tab "Phone Information"
Find the Build Date string (format: MM-DD-YYYY)
Compare the date with the official firmware releases for Redmi 4X
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Example: If the menu says Build Date: 03-15-2017, the phone is assembled no later than March 2017, but this method only works for original firmware. If the device has been reflashed, the date will indicate the software version, not the production.
⚠️ Note: Some custom firmware (e.g. LineageOS) may not have the Build Date string or show the firmware build date rather than the phone.
Alternative code for verifying hardware information: ##225##. It shows display calibration data, which sometimes indicates the date of testing at the factory.
Yeah, I always check.
No, I didn't know about that possibility.
I checked, but I didn't understand the results.
I don't care.-->
Method 4: Analysis of MIUI version and hardware
The MIUI version and the hardware revision indirectly indicate the release date. The following matches are relevant for the Redmi 4X:
| MIUI version | Hardware audit | Approximate year of issue | Features |
|---|---|---|---|
| MIUI 8.2 – 8.5 | Rev 1.0 | 2017 (first batches) | Snapdragon 435 processor with the MSM8940 marking |
| MIUI 9.2 – 9.6 | Rev 1.1 – 1.2 | 2017 (mid) | Improved Wi-Fi antenna, another memory provider |
| MIUI 10.1+ | Rev 1.3+ | 2018 | Support for VoLTE for the European market |
To find out the hardware audit:
- Install the AIDA64 or CPU-Z app.
- Go to Motherboard or Hardware Info.
- Find the Hardware Revision line.
If the revision is 1.0, the phone was released in the first quarter of 2017.Reversions 1.3 and higher date back to 2018 and have improved thermopaste on the processor.
Method 5: Checking by Battery batch number
The Redmi 4X battery has a marking that allows you to determine the date of its production (usually close to the date of assembly of the phone).
- XXYYMMDD – where YY year, MM month, DD day.
- LOT: XXXXXXX is a batch (the first 2 digits may indicate a year).
Examples:
- B6170315 → March 2017.
- LOT: 18051234 → May 2018.
⚠️ Note: If the battery has already been replaced, the date will not match the date of the phone, in which case, look for the original sticker under the battery, which may have the serial number of the device on it.
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Batteries Redmi 4X 2017 release have a capacity of 4100 mAh, and the late batch (2018) — 4000 mAh.
Frequent Mistakes and How to Avoid Them
When determining the release year of Redmi 4X, users often make the following mistakes:
- 🔄 You confuse the firmware date (in settings) with the production date. You can update the firmware and the build date doesn't.
- 📦 They only trust the box without checking the serial number on the phone.
- 🔋 They think the date is on the battery. = The phone's date, the battery could have been replaced.
- 📱 They use apps like the phone. INFO, Incorrect data for Chinese devices.
To avoid mistakes:
- Check data from at least two sources (e.g. serial number + box).
- For the Chinese version (Redmi 4X China), the firmware date can be 1-2 months later than the actual date.
- If the serial number is erased or not readable, use IMEI to check on imei.info.
An example of a typical scam: the seller shows a box with a date of 2018, but the serial number of the phone starts with 17 (2017), in which case the phone is exactly older than stated.