Turn off automatic remediation. The interface checker should report only. All fixes require human approval. This alone stops 99% of catastrophic errors.
Detailed troubleshooting and community advice can be found on the French Car Forum or technical guides on firmware version download, or are you having trouble with a particular car model PSA interface checker - French Car Forum
to identify the device. You should see "INIT OK" if it's detected. Check your version/reference (e.g., Revision B or C). Select & Flash Firmware "Select File" and choose a stable firmware version (commonly are used to restore functionality). "Downloading."
The classic scenario: