Understanding when and why the PSA Interface Checker 440 2021 appears is the first step toward resolution. Here are the five most frequent triggers:
If you are still on a 2020 or earlier release, the interface checker may use outdated session handling. Upgrade to at least the 2021 feature pack to benefit from improved token management and clearer error codes. psa+interface+checker+440+2021
: Newer versions of DiagBox require the VCI to run firmware version 4.4.0 (or later) to communicate with modern vehicles. Understanding when and why the PSA Interface Checker