スマホ故障診断 is a free utility and tools app developed by NTT DOCOMO INC. for iPhone users. This app allows users to diagnose potential malfunctions in their iPhone devices. Users can select up to three symptoms and the app will automatically diagnose whether there is a malfunction or not. Even if there are no specific symptoms, the app can still diagnose the functionality of communication, GPS, sensors, and more. If there are four or more symptoms, users are advised to perform the diagnosis again from the app's home screen.

The app provides users with improvement suggestions and guidance for repair, replacement, or model change based on the diagnosis results. With its user-friendly interface, anyone can easily use this app to diagnose potential issues with their iPhone devices.