Some parts of a CAN frame have an expected format. A form-error report means the receiver or decoder did not see that expected structure.

How to narrow it down

Start by preserving the original trace and checking that the selected protocol matches the network. Compare several events rather than making a repair decision from one highlighted frame. Note whether the error appeared only after test equipment was connected or settings changed.

What to include with the fault report

Send a short raw capture that includes traffic before and after the reported error.

A report should say whether the result came from a vehicle controller or an offline decoder. Those are different observations and may need different follow-up checks.

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 Kvaser. The referenced design explains the principle; the vehicle-specific procedure determines the repair.