The method presented applies to the analysis of the indicated constituents in diesel engine exhaust@ or vehicles using diesel engines@ when operating at steady-state conditions. The measurements of carbon monoxide@ carbon dioxide@ and nitric oxide are based on continuous sampling and analysis by nondispersive infrared methods. A supplementary bath sampling@ wet chemistry method is described for analysis of the oxides of nitrogen. Purpose- This SAE Recommended Practice provides for the measurement of carbon dioxide@ carbon monoxide@ and oxides of nitrogen in diesel exhaust.