Component of 1,2-phenylacetyl-CoA epoxidase multicomponent enzyme system which catalyzes the reduction of phenylacetyl-CoA (PA-CoA) to form 1,2-epoxyphenylacetyl-CoA. The subunit E is a reductase with a preference for NADPH and FAD, capable of reducing cytochrome c. Binds 1 [2Fe-2S] cluster. Aromatic compound metabolism; phenylacetate degradation. Activated by cAMP receptor protein (CRP), integration host factor (IHF) and by phenylacetyl-coenzyme A (PA-CoA) that prevents PaaX from binding its target sequences. Inhibited by PaaX. In the N-terminal section; belongs to the FAD-binding oxidoreductase type 6 family.