How to tell if a session is KWP2K or UDS

How to differentiate KWP2K and UDS

Both UDS and KWP2K on CAN run over ISO-TP (ISO-15675-2). Even though they might look pretty similar, the SIDs (Service IDs) do differ, as well as their parameters. A quick and easy way to differentiate them is by the accepted Diagnostics Session levels. A device running an UDS server will most likely accept Session levels that are below 0x80, the most common one being 0x01 (Standard UDS Session).

A device running a KWP2K server will most likely accept Session levels that are above 0x80, the most common being 0x81.

If you are unsure of what kind of Diagnostics Service is your DUT (Device Under Test) hosting, either scan or try to start a diagnostics session that is default for the specific protocol.