The present disclosure generally provides an emission treatment system for at least partial conversion of gaseous CO emissions. The exhaust gas treatment system includes various components such as a first catalyst component selected from a LNT or an oxidation catalyst for the abatement of HC and CO, which contains a catalyst composition such as a platinum group metal component impregnated into a refractory oxide material. Another component in the exhaust gas treatment system is an SCR catalyst for the abatement of NOx, which contains a catalyst composition such as a metal ion-exchanged molecular sieve and can be optionally absent when the first catalyst component is an LNT. A second oxidation catalyst for further abatement of CO is also part of the emission treatment system and includes a third catalyst composition selected from a platinum group metal component, a base metal oxide component, or combinations thereof disposed onto a carrier substrate.