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We present a high resolution X-ray spectrum of the accreting X-ray pulsar,OAO 1657--415 with HETG+ACIS-S onboard \emph{Chandra},revealing the presence ofa broad line component around $\sim$ 6.3 keV associated with the neutral ironK$_\alpha$ line at 6.4 \rm{keV}. This is interpreted as Compton shoulderarising from the Compton scattering of the 6.4 \rm{keV} fluorescence photonsmaking OAO 1657--415 the second accreting neutron star where such a feature isdetected. A Compton shoulder reveals the presence of dense matter surroundingthe X-ray source. We did not detect any periodicity in the lightcurve andobtained an upper limit of $\sim$ 2\% for the pulse fraction during thisobservation. This could be due to the smearing of the pulses when X-ray photonsare scattered from a large region around the neutron star. In addition to theFe K$_\alpha$, Fe $K_\beta$ and Ni $K_\alpha$ lines already reported for thissource, we also report for the first time, the presence of He-like and H-likeiron emission lines at 6.7 and 6.97 \rm{keV} in the first order HETG spectrum.The detection of such ionized lines, indicative of a highly ionized surroundingmedium, is rare in X-ray binaries.

Multitude of iron lines including a Compton scattered component in OAO 1657--415 detected with Chandra