How to test sensors on a used Android phone

A used Android phone can look fine while a motion sensor, compass or vibration motor is unreliable. A few simple checks can show whether the readings respond as you move the phone, or whether the browser cannot access them.

Use the Sensors Test on the phone itself. It checks motion, gyroscope, compass, light, location and vibration, although Android models and browsers do not expose every sensor in the same way.

Test the phone's sensors

1. Open the Sensors Test in a browser on the Android phone. Testing on the phone matters because a browser on another device cannot read this phone's sensors.
2. Allow any browser permission the test requests. Location needs location permission. If the browser offers a choice, allow access for this site while using it.
3. Hold the phone flat and still, then tilt it slowly forward, backward and to each side. Watch the motion and gyroscope readings for changes as the phone moves.
4. Turn the phone through a full circle, first flat and then upright. Check whether the compass reading changes smoothly with direction. Move away from speakers, metal furniture and other objects that may affect a compass.
5. Check the light sensor in a steady room, then cover the top front edge of the phone briefly and uncover it. The reading should respond to the change in light if the phone has an accessible light sensor.
6. Try the location and vibration checks if they are available. For location, compare the result in a place where the phone can get a clear location fix. For vibration, keep the phone in your hand and notice whether it vibrates when the test requests it.

Use gentle movements and keep the phone secure. You do not need to shake it hard or run the phone near water, stairs or traffic to test its sensors.

What the result means

Motion readings change as you tilt the phone

The motion sensors are responding to movement. This is a useful basic check, but it does not prove that every sensor is calibrated correctly or that an app will interpret its readings the same way.

The gyroscope or motion reading stays still

First make sure the phone is actually moving and that the browser has not paused the page. If the reading still does not respond after reloading and checking permissions, the phone may not provide that sensor to the browser. Some models omit particular sensors, so a missing reading is not proof of damage by itself.

The compass changes, but points the wrong way

A direction reading can be disturbed by nearby metal or magnetic accessories, and it may need calibration. Take off a magnetic case, move away from metal objects and repeat the turn. If it remains far off in several locations, the compass sensor or its calibration may be faulty.

The light reading does not change

The phone may not expose a light sensor to the browser, or the sensor may sit somewhere other than the area you covered. Try changing the room lighting and covering the top edge again. If the reading remains unchanged, compare it with automatic screen brightness behavior, which can use a different software path.

Location is missing or inaccurate

A browser location result depends on permission and available location sources, not just a dedicated phone sensor. Indoors, accuracy may be limited. Turn on Android location, allow the browser to use it, and try again near a window or outdoors. A missing browser reading alone does not establish that the phone's GPS hardware is broken.

Vibration does not happen

The browser or phone may block vibration, or the device may not provide the needed browser feature. Check the phone's vibration settings and try again. If the phone also fails to vibrate for incoming calls or its own system controls, a hardware fault becomes more likely.

How to fix access or missing readings

1. Reload the test. Close the page, open it again and repeat the movement. A page that has been left in the background may not receive live sensor updates.
2. Allow location for the browser. On Android, open Settings › Location and turn on location. Then open Settings › Apps › Chrome › Permissions › Location and allow it while using the app. Menu names can differ by phone maker and Android version. If you use another browser, choose that browser instead of Chrome.
3. Check the site's permission. In the browser, open the site's controls beside the address bar and review its permissions. Allow location if it is blocked, then reload the page. Browser menus vary, so look for the site's permission or site settings screen.
4. Remove magnetic accessories. Take off a magnetic case or wallet and move away from speakers, metal stands and magnetic mounts before testing the compass again.
5. Check vibration settings. Open Settings › Sound & vibration and make sure vibration is enabled. The exact path and setting names vary across Android phones. Turn off Do Not Disturb temporarily if it is suppressing vibration.
6. Restart the phone and try again. Restarting can clear a temporary browser or sensor service issue. After restart, open the test in the browser and grant any permissions again.
7. Try another browser on the same phone. If a sensor appears in one browser but not another, the difference points to browser support or permission handling rather than a definite hardware failure.

When a sensor may be faulty

A hardware problem is more likely when the same sensor fails repeatedly after permissions are allowed, the phone has been restarted, and magnetic accessories have been removed. Look for matching symptoms in normal phone use too: for example, a compass that is consistently wrong in different places, motion-controlled features that never react, or no vibration for system alerts.

Before buying the phone, repeat the checks yourself and note which sensors respond. If a key sensor fails in ordinary use as well as in the browser, ask the seller about repair history or return options. A phone under warranty should go through the manufacturer or seller. For an older phone, get a repair estimate before paying to replace a sensor assembly.

Why a browser test can miss a working sensor

A browser can only read sensor information that Android and the browser make available to a web page. The phone may have hardware that the browser does not expose, and location depends on permission and signal conditions. Vibration can also be restricted by the browser or operating system. Treat a responsive result as evidence that a sensor is providing data, and a missing result as a reason to check access before assuming the part is broken.

The Sensors Test runs in your browser on the phone, but location access still depends on the permission you grant and the conditions around you.