A tanker's Class 8 Corrosive placard is still in the correct position and shows the right hazard class, but UV exposure has faded it so badly that the number in the lower corner is no longer readable. What is the compliance issue, and what is the approximate penalty range?

49 CFR 172.516(c) (duty to maintain placards legible and undamaged); ELDT Penalty Reference (Part 2, Placarding Violations)

A placard that's technically there but can't actually be read fails the entire purpose of placarding, which is letting first responders instantly identify a hazard. This is also a cheap, avoidable violation; a quick pre-trip check of placard condition prevents an otherwise unnecessary fine.