With ColorOS 13 and above (although A9 2020 stopped at ColorOS 7), many manufacturers are hiding engineering codes for security reasons. However, the OPPO A9 2020 remains a device where . They offer a level of insight and control that no third-party app can match, especially for hardware diagnostics.
Before diving into the specific codes, it is essential to understand what they are. USSD (Unstructured Supplementary Service Data) codes are short strings of characters that you type into your phone’s dialer. These codes communicate directly with your phone’s firmware or your network provider. How to Use Secret Codes on OPPO A9 2020