How do you seize a white plastic tool box on front of caravan white again, as it have gone wan contained by the sun!?
You can't as the sun damage is not simply on the surface. You would have to find some way to recoat the tool box and this would gross it look different. The damage to plastic color due to UV rays is irreversible.Only paint will improve it.
you will have to paint it im afraid.
the yellowness is where the UV from the sun have broken down the polymer chains in the plastic and this is not reversable.
You could try uPVC cleaner, it might assistance
An alkaline base detergent works well in most cases, I hold the same problem with the entry door on my RV. Hope this help... It's very simple - buy a new one - this is cause by permanent damage from UV radiation. Sorry!
Answers: Does it matter? It might be better to just depart it. Painting it might look messy.