Transforms 2,4-dichlorophenol (2,4-DCP) into 3,5-dichlorocatechol. 2,4-dichlorophenol + H(+) + NADPH + O2 = 3,5-dichlorocatechol + H2O + NADP(+) Xenobiotic degradation; (2,4-dichlorophenoxy)acetate degradation. Homotetramer. Belongs to the PheA/TfdB FAD monooxygenase family.