Negative response code 0x25 identifies a missing response from a required subnet component. The module answering the diagnostic tool may be reporting a problem elsewhere.
How to narrow it down
Use a complete network scan to identify the expected downstream unit and its availability. Check the relevant power, network and vehicle configuration before replacing the gateway that reported the response. Preserve the topology and fault history, particularly after module or wiring changes.
What to include with the fault report
Include the vehicle scan and the operation that required the missing component.
The code does not name the physical cause. A missing response can require vehicle-level testing beyond an isolated module assessment.
Speak to AXION
For module programming and coding support, 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 response 0x26 when an existing fault prevents an operation. Browse all vehicle-electronics diagnostic notes or return to the repair library.