How to get an FWL file out of E-Sys

In E-Sys, read out the ECU, then open the FDL editor for it. From there you can export the current coding as an FWL file — a plain-text dump of every parameter and its value, which is what this tool reads. You don't need to flash anything to export; it's just a snapshot of the coding as it currently sits in the FDL editor.

This is especially handy for working out what a specific option code actually does. Export an FWL before you flip an option (or toggle any FDL parameters) and another FWL after, then drop both files in below. Everything that's identical between the two gets hidden by default, so you're left with exactly the parameters that option touched — which modules, which bits, and what they flipped to. Same trick works for comparing two different VINs, checking what a retrofit or coding profile actually changed, or sanity-checking your own coding before you write it back to the car.