UDS response 0x12 concerns an unsupported subfunction of a diagnostic service. It does not automatically mean all communication with the module has failed.

What to check next

Note which other supported operations still work. Compare the requested test with the exact vehicle configuration and tool coverage. This distinction matters when a replacement module communicates normally but a particular menu option is refused.

Useful information for an enquiry

Keep the complete operation log and both module identifiers if a replacement was fitted.

Do not try unrelated commands to discover a workaround. A supported diagnostic route is safer and produces a result that can be interpreted properly.

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.

Related reading — UDS 0x13 incorrect length or format in a tool report. Browse all vehicle-electronics diagnostic notes or return to the repair library.