Exhaust gas analyzer Exhaust gas analyzer An exhaust gas analyser or exhaust CO analyser is an instrument for the measurement of carbon monoxide among other gases in the exhaust, caused by an incorrect combustion, the Lambda coefficient measurement is the most common. The principles used for CO sensors (and other types of gas) are infrared gas sensors (NDIR) and chemical gas sensors. "Carbon monoxide sensors are" used to assess the CO amount during an MOT test. In order to be used for such test it must be approved as suitable for use in the scheme. In UK a list of acceptable exhaust gas
Exhaust gas recirculation Clogged EGR valves can sometimes be cleaned, but replacement is necessary if the valve is faulty. In modern diesel engines, the EGR gas is cooled with a heat exchanger to allow the introduction of a greater mass of recirculated gas. Unlike spark-ignition engines, diesels are not limited by the need for a contiguous flamefront; furthermore, since diesels always operate with excess air, they benefit from EGR rates as high as 50% (at idle, when there is otherwise a large excess of air) in controlling NOx emissions. Exhaust recirculated back into the cylinder can increase engine wear as carbon particulates wash