Ghost touch issue on iPhone XS Max

A ghost touch issue is the result of a failed digitizer. The digitizer is built into the screen and a screen replacement will resolve that problem. Schedule an appointment for diagnosis and repair at Apple.

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We can't diagnose your phone from our sofas. Ghost Touch is certainly possible, especially on a phone which was released by Apple in 2018, 7 years ago. You have a very old phone at this point. If the battery has never been replaced, it's hugely likely it needed to be replaced long ago. The digitizer on your screen could be failing. Whatever may be causing an issue, it can't really be solved here. But if it was my phone, knowing that iOS 26 is forthcoming and it will no longer be able to be updated past iOS 18.6.2 would have me looking at buying a new iPhone at this point.