The last part of a segmented message may need fewer data bytes than preceding frames. A shorter final frame is not automatically a damaged CAN message.

How to narrow it down

Compare its length with the total payload announced at the start and the applicable padding rules. A decoder should assemble the message using transport information rather than assuming every frame contains an equal amount of useful data.

What to include with the fault report

Send the initial frame and the complete sequence through the final frame.

The same short length in the middle of a transfer may need a different interpretation. Position and protocol rules both matter.

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 python-can-isotp. The referenced design explains the principle; the vehicle-specific procedure determines the repair.