In addition, Doosan dealers can provide improved customer support using the system by responding to machine warning messages and alerts, troubleshooting machine issues and then sending a field service vehicle to help with repairs and deliver the proper parts. Tier 4 solution The Doosan DX170LC-5 complies with Tier 4 emission standards with modified diesel engine and aftertreatment technologies. The engine is optimized for use with a high-pressure common-rail (HPCR) fuel delivery system and a cooled exhaust gas recirculation (CEGR) system. It uses a diesel oxidation catalyst (DOC) to reduce particulate matter (PM) and selective catalyst reduction (SCR) aftertreatment to reduce nitrogen oxides (NOx). Additionally, a variety of aftertreatment systems have been implemented as part of Tier 4 compliance, such as DEF, which is used with SCR technology.