if it ain’t broke don’t fix it

If something is already or still working, leave it as it is.

If it ain’t broke don’t fix it, the car still works so do not buy a new one.

Your interference in this matter is not appreciated because if it ain't broke, don't fix it.

I always tell my husband to not meddle in the children's lives anymore until they come to us for help. If it ain't broke, don't fix it.