: Users can manually "flash" the interface to a different firmware version to solve communication errors with specific vehicle modules, such as the ECU.

DiagBox versions 7.xx to 9.xx perform active hardware checks. If the interface checker fails at the “440” level, DiagBox will enter “degraded mode,” hiding critical functions like telecoding and parameter adjustments.

PSA Interface Checker is a specialized utility used to verify and manage the firmware and hardware revision of the Vehicle Communication Interface (VCI) used for Peugeot, Citroën, and DS vehicle diagnostics. French Car Forum

Modern versions of Diagbox (v7.xx and v9.xx) frequently require firmware 4.4.0 to maintain a stable connection with newer Peugeot and Citroën models.