Always test Samsung Android devices before buy it (only valid for shop purchase though). Yes, this applies to Samsung flagship Galaxy S4 too. Samsung makes a great tool for them to check the hardware quality at test development stage. And you can use it to test too. The application is called FactoryKeystring. Basically, it covers all the hardware function tests for Galaxy S4. You can check 1080p Full HD Super AMOLED screen with Red, Green, Blue, Receiver (white) and Vibration (black) colour. Make sure that there is no dead or bright pixel. That’s the first thing I will do. I really hate dead pixel as it is very annoying. There are other tests like Dimming, Touch and TSP Hovering to test the screen function as well. Front and back camera can be tested with Mega cam and Front cam. Both speakers’ tests are included too. Sleep, Sub key, LED, IR LED, LOW FREQUENCY, Barcode Emulator and SensorHub Test are the rest of the tests. Test all of them if you can.

How to test Galaxy S4 hardware functions?
- Click on Phone.
- Bring up Keypad.
- Key in *#0*#.
- It will load FactoryKeystring app.
- Run all the tests there.
- That’s it.

Luckily, I did run all the tests before leave the shop. I discovered that my first Galaxy S4 failed to perform Air View (TSP Hovering) properly. It failed to sense left part of the screen. It can cover half of the left box only unlike the screenshot above (my 2nd set) which can cover the whole block. Therefore, make sure that you test your new Galaxy S4 properly before leave shop…
thanks for the tip
omg, if i order online fr digi then i guess is too bad if i get defective s4
Ask for exchange first. Else need to RMA. No worry much, Samsung quality control is quite good.
what or how to test Power Noise Test? (under sensor)
Sorry jc, I have no idea too.
did u get a fail test result đŸ˜›
Yes because don’t know how to test it as well.
Hello,
What is the ideal CPU temperature for galaxy s4 when playing games?
I used TempMonitor v3.1.0:
https://play.google.com/store/apps/details?id=org.alldroid.apps.tempmonitor&hl=en
and I got 55-63 degrees. Can you tell me how much you get on your device please? Appreciate it, thanks.
Sorry, I don’t have TempMonitor v3.1.0. As it does not support GT-I9500.
https://www.jayceooi.com/2013/05/20/how-to-check-galaxy-s4-cpu-temperature/
But what is the ideal temperature while playing games?
Depend on your room temperature… Like my room at 28 °C, my Galaxy S4 easily hit over 50 °C when playing 3D games.
So, is my temperature ok or should I contact samsung for warranty? My temperature is above 55 upto 63 degrees while playing temple run. It is above 50 even when I use live wallpapers.
Feel free to contact Samsung Support if you feel not comfortable with it.