EGR: why some of the exhaust comes back

Useful to know

The external EGR system returns some of the exhaust to the intake side via an additional path and valve. HELLA explains that this is different from the internal recirculation associated with the operation and overlap of valves in the engine. [1]

The goal is not just "dirty air instead of clean". The controlled quantity is involved in the combustion process and the limitation of certain emissions. The specific strategy depends on the engine and mode, so one value for EGR is not a common standard for all cars.

When complaining about unequal work, it is not enough to indicate EGR as a popular explanation. You need to check the real data and the whole connected system. The text explains the function and the distinction between internal and external recirculation without offering removal, clogging, or software shutdown of components.