Glossary “exhaust gas oxygen” Definition:
Amount of oxygen present in the exhaust stream, as measured by an oxygen sensor and reported to the computer in closed-loop, feedback systems to aid in the control of the air/fuel mixture.

Glossary “exhaust gas recirculation (EGR)” Definition:
Process of passing a small, measured amount of exhaust gas back into the cylinders to reduce combustion temperatures and formation of Nox.

Glossary “exhaust gas recirculation (EGR)” Definition:
Emissions control system that reduces an engine’s production of NOx by diluting the air/fuel mixture with exhaust gas so that peak combustion temperatures in the cylinders are lowered.

Glossary “exhaust gas recirculation valve (EGR valve)” Definition:
Valve, that is generally vacuum operated, to regulate the exhaust gas flow into the intake manifold.

Glossary “exhaust analyzer” Definition:
Automotive test and service device that uses a process involving infrared energy and sensors to determine and display the composition of an engine’s exhaust gases, such as: HC, CO, CO2, O2, and NOx. Some types may also measure sulpher compounds and particulates.

Glossary “exhaust back pressure” Definition:
The resistance of the free flow of gas in the exhaust system.

Glossary “exhaust back pressure testing” Definition:
Test of the exhaust system to determine the amount of exhaust restriction

Glossary “exhaust emissions” Definition:
Pollutants that are the result or by-product of combustion.

Glossary “exhaust gas” Definition:
Burned and unburned gases that remain after combustion.

Glossary “exhaust gas analyzer” Definition:
Instrument for determining the amount of HC, CO, CO2, O2, and NOx emitted into the atmosphere.