This problem can have several reasons, ranging from misconfigured settings to an improperly installed screen protector. But these reasons shouldn't require you to manually adjust the brightness. We have put together some effective troubleshooting tips that will help you fix the auto-brightness not working issue on iPhone. Without further ado, let's check them out.

1. Remove the screen protector

Your iPhone uses the built-in ambient light sensor to detect your current lighting conditions and adjusts the brightness accordingly. Your screen protector may be blocking this sensor and preventing your iPhone from adjusting the brightness. Therefore, you should remove any screen protector to see if it helps.

Likewise, if you're using a protective case that covers the sensors at the top, consider removing that as well.

2. Clean your iPhone

Once you've removed the screen protector and the case, cleaning your iPhone with a soft, dry cloth should be your next step. The built-in ambient light sensor is located at the top of the notch. Cleaning it should help remove any sweat or oil that may have coated the sensor.

No chance? We still have many other solutions to try.

3. Toggle auto-brightness

Next, it's time to refresh the auto-brightness setting on the iPhone. You may have done it before, but it's worth a try.

Step 1: Open Settings app on iPhone and go to Accessibility.

Step 2: Under Vision, select Display and Text Size. Scroll to the end of the page and turn off the switch next to Auto-Brightness.

Restart your iPhone and then enable auto-brightness by following the steps above.

4. Disable Low Light Mode

If you used the Screen Zoom feature on your iPhone to improve readability, it may interfere with the auto-brightness feature. Specifically, if you accidentally turned on low light mode, your iPhone's brightness will remain low all the time. Here's how to change that.

Step 1: Open the Settings menu on your iPhone. Go to Accessibility and press Zoom.

Step 2: Tap Zoom Filter and make sure it's not set to Low Light.

Check if the auto-brightness function works.

5. Disable Night Shift

Similar to Screen Zoom, the Night Shift feature is also known to sometimes interfere with the auto-brightness feature. If you've used this feature to reduce the blue light coming from your iPhone, consider turning it off by following the steps below.

Step 1: Launch the Settings app and go to Display & Brightness.

Step 2: Open Night shift settings. Next, turn off the switch next to Manually activate until tomorrow and Scheduled.

6. Update iOS

If you haven't updated iOS in a while, now would be a good time. If you've been waiting to update your iPhone's iOS version, there might be a problem with auto-brightness. Check for pending iOS updates and install them.

To check for software updates on iPhone, open the Settings app. Go to General and select Software Update from the menu.

Download and install any pending updates and check if your iPhone can automatically adjust the brightness.

7. Quit iOS beta

It's not just using an older version that can cause problems. Using beta versions of iOS, intended for early adopters, can also lead to such issues. Several iPhone users who were on iOS 15.2 Beta complained about the auto-brightness feature not working. Luckily, the issue was resolved once they upgraded to a stable release.

You should consider upgrading to a stable version to fix auto-brightness feature on iPhone.

Automate and relax

There is no correct setting when it comes to screen brightness. As you move between different lighting conditions, your screen brightness should automatically adjust for a comfortable viewing experience.

Although such problems with the auto-brightness feature may require you to adjust the brightness manually all the time, the solutions above should help you fix them easily.