nokia lumia 900 review

DIAGNOSTIC MODE – # # 6 3 4 #

Enables the following test modes for your device

Accelerometer
ALS
Audio Loopback
DTMF
Hardware Buttons
Bluetooth
Camera
Battery Status
Headset Detection
LCD White
Lights
Magnetometer
Power Source
Proximity
Speaker
Touch
Vibration
Some Users have reported that this App is actually a battery drainer, so its wise to uninstall it after you have done your tests, it can always be installed back with the code ##634#