SAE J 254

This SAE Recommended Practice establishes uniform laboratory techniques for the continuous and bag-sample measurement of various constituents in the exhaust gas of the gasoline engines installed in passenger cars and light-duty trucks. The report concentrates on the measurement of the following components in exhaust gas: hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2), and nitrogen oxides (NOx). NOx is the sum of nitric oxide (NO) and nitrogen dioxide (NO2). A complete procedure for testing vehicles may be found in sAE J1094.