Seat Leon System Readiness Check Issue

Sounds like an OBD readiness issue. I had something similar with my old Volvo V70 after I cleared some codes. The car's computer needs to run a series of self-tests, and those tests need specific driving conditions to complete. Think of it like trying to get all the ingredients for a cake. If you are missing the eggs it won't bake.

So, if I understand correctly, the computer needs to do some internal checks, and these checks weren't done because of the OBD reset? How long or how much do I need to drive until these checks are completed?

Yeah, that's the gist of it. It's all about completing the onboard diagnostics. I never got it to work on my own. I just took it to a workshop, and they told me to drive a particular drive cycle. They did some computer reset as well to make sure it was properly set. After some time, it disappeared. It's annoying but usually not a real problem.

Just wanted to let you know I sorted it. Turns out it was exactly as you described. I took it for a longer drive, and the system readiness check completed itself. No more error message. Thanks for the help!