2-oxoglutarate(2OG)-dependent dioxygenase that catalyzes the conversion of 2-oxoglutarate to succinate and CO(2) in an iron-dependent manner (PubMed:21530488). However, does not couple 2OG turnover to the hydroxylation of acyl-coenzyme A derivatives, implying that it is not directly involved in phytanoyl coenzyme-A metabolism (PubMed:21530488). Does not show detectable activity towards fatty acid CoA thioesters (PubMed:21530488). Isoform 2 probably lacks enzyme activity. Isoform 3 probably lacks enzyme activity. Activity is increased by ascorbate. Inhibited by myristoyl-CoA. Belongs to the PhyH family. PHYHD1 subfamily.