How to Test Used Samsung Galaxy S4 S3 Before Buying It

If you are going to buy a used Samsung galaxy s4 or s3 phone from anyone then you must check it visually and hardware functionality as well. Samsung made it easy to test core hardware functions easily by adding a diagnostic menu. To find how to test Galaxy S4, or S3 hardware function continue reading.

See Also How to Factory Reset Samsung Galaxy S4

There is a service code that you can dial on your phone to access this diagnostic menu and perform different hardware functionality tests on your phone. You can perform test like screen test including screen colors and Touch functions, Vibration, Receiver, Sensors, Speakers, Keys, front and rear cams, Led lights and more.


Dial *#0*# from your phone and you will see the following screen with 15 different hardware test buttons.


Tap on each button to perform test and to get back to this menu you either need to tap the screen or hit the back button two times on you Galaxy S4 or S3.

  • On this diagnostic menu first row to buttons Red, Green and Blue are the screen color tests that shows any dead pixels of the screen or tinted effect if any.
  • Test Phone Receiver : By pressing Receiver button you will hear a beep that shows receiver working fine and if you don’t hear any beep then phone might have problem with its receiver.
  • Test Vibrator : Vibration button will test the phone vibrator and your phone will vibrate continuously to stop it press the back button or tap the screen.
  • Screen Dimming Test : Dimming button and you will see phone screen divided with RGB gradient colors, tap again on the screen and screen should be half dimmed, hit the back button two times to go back.
  • Back/Rear Camera Test : Mega cam button used to test phone’s rear camera, tap this button check the camera view, perform focus test and take a picture.
  • Sensors Test : Using Sensor button you can perform all sensor test on your phone including Accelerometer, Proximity, Barometer, Lights, Gyroscope, and Magnetic Sensor.
  • Touch Screen Test : Touch is major test on the phone, tap it and touch each box on the screen to fill it with green color. If all filled with green then screen touch test is passed.
  • Sleep button will test your phone’s sleeps functionality, once you tap it to test your phone will be in sleep more and you need to wake-up with power or home button.
  • Speaker Test : Hit the Speaker button to test phone speakers, when you hit the speaker button you will hear repeating sound until you tap this button again.
  • Phone Keys Test : Sub key button used to test the keys on the right and left sides of the home button
  • Front cam is similar to Mega cam button.
  • LED Light Tests : LED is test to check phone’s alert LED light.
  • Low Frequency button used to perform different LCD frequency tests.

By doing all these test you can test and diagnose your own device and also test a used Galaxy S4 or S3 phone that you are going to buy.

1 comment… add one
Trevor December 22, 2014, 8:35 pm

AWESOME tip, thanks!

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