UDS response 0x31 indicates that the requested parameters are outside what the server accepts in that context. It does not identify a failed electronic component.

How to narrow it down

Compare the requested function and dataset with the vehicle and controller identity. Keep any donor-module or prior coding history visible. A value accepted by a similar car may not be applicable to this hardware or software version.

What to include with the fault report

Send the exact operation and full rejection, without publishing protected identifiers or access credentials.

Compatibility and supported procedure come before another attempt. The response should not be used as a reason to bypass protected functions or substitute an unknown file.

Speak to AXION

For CAN-bus and vehicle-network diagnostics, send your vehicle details and fault report. Workshop assessment is in Didcot, Oxfordshire. Suitable postal or remote work is confirmed before booking.

Technical background from py-uds. The referenced design explains the principle; the vehicle-specific procedure determines the repair.