While Toyota rarely releases exhaustive public changelogs for every minor version, user reports and technical bulletins suggest that the DA31 update focuses on:
The 17TDT1EU-DA31 firmware update enhances system stability and smartphone integration for the Toyota Touch 2 multimedia system in European Toyota C-HR models. The update can be applied via Over-the-Air (OTA) updates through the vehicle's menu or by USB manual installation. Read the full story at Toyota UK Magazine . 17tdt1eu-da31 Software Update
The alphanumeric code "17TDT1EU-DA31" identifies the software version for the market. 17tdt1eu-da31 Software Update
Most owners can perform this update at home using a standard USB drive. Toyota often provides these patches for through their customer portals. Preparation: 17tdt1eu-da31 Software Update