Abstract: An apparatus and method are disclosed for sampling and analyzing the exhaust gas or liquid from an internal combustion engine or other device that generates a flow of exhaust gas or liquid during use. The apparatus includes a connector that is adapted to be secured adjacent to an aperture formed through an outlet conduit of an engine or other device that generates a flow of exhaust gas or liquid therethrough during use. A conduit communicates with the connector and is adapted to receive and pass therethrough at least a portion of the exhaust gas or liquid from the outlet conduit. A sensor chamber communicates with the conduit and is adapted to receive and pass therethrough at least a portion of the exhaust gas or liquid from the conduit. A one-way valve only allows the exhaust gas or liquid in the sensor chamber to exit therefrom. Lastly, a sensor senses at least one characteristic of the exhaust gas or liquid in the sensor chamber and generates a signal that is representative of such characteristic.