LG K40 Hidden Menu Codes – LM-X420MM, LMX420AS, LMX420TM & LMX420QN

LG K40 comes in 4 different variants. It’s available for MetroPCS, T-Mobile & AT&T. The 4th one is the Factory Unlocked Version.

There are 2 different Hidden Menus available for the MetroPCS/T-Mobile variant. The rest of the K40 variants have a single Hidden Menu. In this post, we’re going to unhide the Secret Menus and explore them in great detail as per the video and screenshots below –

LG K40 Hidden Menu Codes – MetroPCS lmx420mm / AT&T lmx420AS / T-Mobile lmx420tm / Factory Unlocked lmx420qn

lg k40 hidden menu device test

The first Hidden Menu code is common for all the K40 variants and this is the Main Hidden Menu with lots of troubleshooting options in the form of Device Tests.

To get access to this Hidden Menu open your K40 phone dialer and dial *#546368#*420#

The 4 options in the Hidden Menu can be seen in the above screenshot. They are “Device Test”, “ORT Test”, “SVC Menu” & “Field Test”. Let’s explore them one by one using the below screenshots –

1.  Device Test – LG K40 Hidden Menu

Go to “Device Test” < “SAAT” < “Service Menu – Manual Test” to view the list of Tests.

a. Auto Detecting Item Test

LG K40 auto detecting item test

The first test in the list is “Auto Detecting Item Test”. Select it to start the test.

To PASS this test you should have a SIM Card and Micro SD card in their respective slots.

In case, the memory card or SIM card is not in the slot, you can skip this test only by pressing the power & volume keys together.

b. Key Press Test

lg k40 hidden menu key press test

This test covers the hardware keys and proximity sensor.

Press each hard key such as Power Key, Volume UP, Volume Down & Google Assistant Key.

The “ETC” option in the last screenshot above represents the Google Assistant Key.

The Proximity Sensor can be tested by blocking and unblocking the sensor as per the instructions on the screen.

The proximity sensor is located above the screen.

c. Display Check Test

lg k40 display check test

This is an LCD test that can help in identifying dead pixels if any.

The screen turns all-black then all-while under this test as shown above.

d. Ring Test

lg k40 speaker not working - ring test

Speaker issues are quite common and this test can help in troubleshooting your LG K40 loudspeaker.

Under this test, the phone rings at the maximum volume even when it’s in the “silent” or “do not disturb” mode.

e. Vibrator Test

lg k40 no vibration - vibrator test

Similar to Ring Test, in this test the phone vibrates at maximum intensity. If it fails you need to replace the vibrator motor on your K40.

f. Motion Sensor Test

lg k40 motion sensor test lmx420

We’ve already tested the Proximity Sensor. In the Motion Sensor Test, we are going to test the rest of the LG K40 sensors which are Magnetometer, Accelerometer & Gyroscope.

To perform this test, Place your K40 on a Flat Surface.

lg k40 gyroscope test

Now, stand the phone vertically and finally horizontally to clear this test.

g. Loopback Test

lg k40 audio loopback test

The next test on our list is the Loopback Test.

As the name suggests, this is a loopback between the audio from earphones and the loudspeaker.


loopback test k40 hidden menu

When one is turned on the other turns off automatically.

h. GPS, Bluetooth & Wifi Test

LG K40 GPS Wifi & Bluetooth Test

Bluetooth, Wifi & GPS issues are quite common in android smartphones.

This test can be quite useful in identifying and troubleshooting network related issues.

i. Touch Draw Test – Manual

LG K40 touch screen test

This is a manual touchscreen test, where we can draw on screen and identify issues related to the LG K40 touchscreen digitizer.

j. Camera (Main) Test

Rear Camera Test LG K40 hidden menu

This is the K40 Rear Camera Test.

Under this test, we have to capture and photo and verify it as shown above.

k. Camcorder Test / Video Recording Test

lg k40 camcorder test

Similar to the Main Camera Test, we’ve to record and verify the video as visible in the above screenshot.

l. Camera (VT) Test / Front Selfie Camera Test

lmx420 selfie camera test

In this test, only the front camera viewfinder is visible. There is no provision to capture an image.

m. FM Radio Test

K40 FM Radio Test Hidden Menu

Connect a headphone in your K40 headphone jack before starting this test. The headphone works as antenna for the FM Radio Test.

n. Finger Print Test

Fingerprint Scanner Test LG K40

Start the test and place your finger on the fingerprint sensor which is located at the back of your K40.

You can see I’ve passed the “SPI”, “Zone”, “Checkboard” and “Rubber Stamp” test as visible above.

2. ORT Test – LG K40 Hidden Menu

LG K40 Hidden Menu ORT Test

The next test in the Hidden Menu after the “Device Test” is the “ORT Test”.

We’re going to change the Mode from Automatic to Manual Mode.

display on off lcd backlight test LG K40

The first test in the test list is the “Display On/Off” test. This is basically an LCD Backlight test. The backlight keeps on turning on and off until you stop it using the stop button.

Display pattern test lg k40 hidden menu

The 2nd test is the Display Patter Test. We’ve to set the time duration for this test as shown above.

LG K40 ORT Manual Test list hidden menu

The rest of the ORT tests are similar to the tests performed earlier. I’m skipping these tests. You can give them a try.

3. SVC Menu – LG K40 Hidden Menu

lg k40 svc menu

The 3rd option in the Hidden Menu is the “SVC Menu”.

It contains similar tests as done before. One interesting test is the Moisture Detection test. When turned on it can alert you in case your phone comes in contact with water.

4. Field Test – LG K40 Hidden Menu

K40 Hidden Menu Field Test - lmx420

The last test in the LG K40 Hidden Menu is the Field Test.

Mostly it contains network-related tests as visible in the above screenshot.


LG K40 Operator Hidden Menu – MetroPCS LM-X420MM / T-Mobile LM-X420TM

lg k40 operator hidden menu

This Hidden Menu code works only on MetroPCS & T-Mobile K40. It won’t work on the AT&T & Factory Unlocked variant of K40.

The second Hidden Menu dialer code for K40 is 277634#*#

The options in this Operator HiddenMenu are more or less the same as the First Hidden Menu that we explored earlier.

Apart from the Hidden Menu, there are 5 more Secret Dialer Codes for LG K40 which are covered in this post.


For any query related to LG K30 & K40, please leave a comment below. Thanks for reading.




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