Check, Diagnose & Understand Your Phone

MobileCodes is a practical reference for understanding, checking and repairing mobile phones. Its core library brings together verified dialler commands, USSD shortcuts and manufacturer diagnostic codes for major brands, with clear descriptions of what each code opens and warnings where an action could change settings or erase data. Instead of presenting an unexplained list, MobileCodes connects each code to the task it can help with, whether that is displaying an IMEI, checking a screen, inspecting battery information or opening a device test menu.

The site also provides guided checks for common hardware and network faults, a free browser-based IMEI validator, and detailed troubleshooting guides for Samsung, Xiaomi, Huawei, Vivo, Oppo, OnePlus and other phones. Those guides explain likely causes, quick checks, brand-specific settings and the point at which professional repair is sensible. Codes are drawn from a curated database rather than invented in an answer, and uncertain or model-dependent support is identified. The aim is simple: help you gather reliable evidence about a problem, try safe fixes in the right order and make a better decision before resetting a phone, replacing a part or paying for a repair.