Android power users often find some odd system APKs pre-installed on their phone that, at first glance, seem to be OEM bloatware. However, some of these apps could be pretty handy as they provide you a set of diagnostic tests to run on your phone. After all, when you send a phone to the manufacturer for servicing, the technicians need testing tools to properly assess the state of the device in order to find out the faulty component(s). The average user can also access a handful of these diagnostic apps by typing the appropriate secret code from the stock dialer app. OnePlus is one brand that comes to mind in this context, as the OEM even offered a downloadable battery health check tool to its users.
OnePlus is famous among tinkerers for having a rich collection of diagnostic tools beyond the battery health checker. As a matter of fact, earlier builds of OxygenOS on devices like the OnePlus 3, 3T, and OnePlus 5 shipped with an extremely low-level diagnostic testing application called “EngineerMode,” which could be exploited to grant root access without unlocking the bootloader. Later on, OnePlus removed the exploitable debugging code, renamed the app to "FactoryMode" (package name: com.oneplus.factorymode), and subsequently blocked its usual execution routine. As a result, you can't simply launch it by dialing *#808# anymore.
XDA's modding community has come to the rescue, though. XDA Senior Member jamal2367 created a Magisk module that enables users to bypass the restriction on the fly and access the powerful Factory Mode app using the *#808# secret code. XDA Senior Member antnyhills, on the other hand, came up with a rather straightforward bypass method that involves editing the config file of the app. There's just one tiny problem: Both methods require root access. Users without root access could try sideloading an older build of the Engineering Mode app on top of the factory-installed one, but those don't always play nice with newer OxygenOS releases.
Fortunately, XDA Senior Member AndroPlus has finally been able to solve the final piece of the puzzle. According to them, OnePlus hides the "FactoryMode" app behind a unique unlock code for every smartphone they produce. The unlock code is derived from the primary IMEI of a OnePlus device. After deciphering how it's generated, AndroPlus wrote an unlock code generator that can unlock access to the Factory Mode app.
How to unlock OnePlus Factory Mode (also known as Engineering Mode)
Warning: Be careful using OnePlus Factory Mode/Engineering Mode. There are many low-level tools and tests here that users aren't meant to access, so you should only do this if you are aware of the risks and know what you're doing.
Note: Keep in mind that the web-based unlocker doesn't store your device's IMEI. That being said, the IMEI of your device is a pretty sensitive piece of information, so don't blindly share it with anyone.
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Dial
*#06#to open up the IMEI information screen on your OnePlus device. Then, long press on the IMEI 1 field to copy it. - Open the unlock code generator by clicking on this link and paste the IMEI in the blank field.
- Press "CONVERT" to get the unlock code.
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Dial
*#*#5646#*#*on your phone. You should see a screen that prompts you to scan a QR code. Press the back button so that you can access the code input field. -
Enter the unlock code in the field and press the "OK" button.
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If everything goes right, you should see the following screen:
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Voila! Now you can access Factory Mode by dialing
*#808#or*#36446337#.
Some older devices (e.g. the OnePlus 7 series) can't take a permanent unlock code. For them, the unlocker offers a special mode named "Unlock for 10 minutes." The resulting code can unlock access to the Factory Mode app for a period of 10 minutes. After that, you have to regenerate the code.
How often do you use the Factory Mode diagnostic suite on your OnePlus smartphone? Let us know in the comments below!