NOVELTY - The system has a reductant supply (50) fluidly connected to a heat exchanger (32). The reductant supply includes methane. A first oxidation catalyst (34) is fluidly connected to the heat exchanger and receives methane from the reductant supply via the exchanger. A second oxidation catalyst (36) is placed within an exhaust passage (26) and receives the exhaust from a diesel-fueled internal combustion engine (12) via the heat exchanger. A clean-up catalyst (38) is placed within the exhaust passage and receives a combined flow, including the exhaust and the methane exiting the first catalyst.    USE - Exhaust system for treating gaseous components e.g. nitrous oxides and carbon monoxide, and solid or liquid components e.g. soluble organic fraction, soot and unburned hydrocarbon, of an exhaust from a diesel-fueled internal combustion engine e.g. diesel engine, petroleum engine or a gaseous fuel-powered engine, and natural gas engine with power systems in a vehicle or machine. Uses include but are not limited to mining application, construction application, mobile or stationary power generation application, and fanning application.    ADVANTAGE - The combustion engine is operated in a high-nitrous oxides mode that can have the desirable effect of virtually eliminating the particulate matter produced during combustion and entrained within the engine exhaust such that the high-nitrous oxides operation eliminates a particulate filter and the active regeneration devices associated with such filters, so that the system can be more compact, less complicated to use and service, thus reducing cost of the system. The system provides heated methane to the engine to improve combustion efficiency in the respective combustion chambers. The system actively regenerates the particulate filter using heating devices that require heating the exhaust to temperatures without causing harm to the catalyst materials used in the oxidation and selective catalytic reduction (SCR) catalysts.    DETAILED DESCRIPTION - The clean-up catalyst comprises a redox catalyst configured to convert the combined flow to nitrogen, carbon dioxide, and water. An INDEPENDENT CLAIM is also included for a method for treating exhaust from a combustion engine.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of a power system.    Diesel-fueled internal combustion engine (12)    Exhaust passage (26)    Heat exchanger (32)    Oxidation catalysts (34, 36)    Clean-up catalyst (38)    Reductant supply (50)