Here you will find a guide to terminology used on this site.

CO. Carbon Monoxide.

CRT. Continuosly Regenerating Trap.

DPF. Diesel Particulate Filter.

Euro 1 to 5. European regulations for Diesel engines.

EGR. Exhaust Gas Recirculation.

HC. Unburned Hydrocarbons.

NOx. Oxides of Nitrogen

PM. Particulate Matter

SCR. Selective Catalytic Reduction.