However, although the EGR system tries to burn all the fuel, it draws the burnt gases along with it while it draws the partially burned gases. However, while the EGR sends the partially burned gases back to the ignition chamber (Partly burned fuels are never like in the first fuel tank and undergo carbonization as they pass through the combustion chamber and are sent to the exhaust section), as it sends the carbonized gas, a sludge-like fuel goes to the ignition / combustion chamber.
In this case, the EGR causes soot after absorbing the partially burned gas, and as the vehicle tries to re-burn the burned gas, it increases fuel consumption and damages the engine health, especially the ignition mechanisms.
In the use of EGR, the formations that will occur in the ignition chamber or your spark plugs will cause your vehicle to not be able to ignite comfortably, thus incomplete ignition and inability to ignite will occur. Therefore, the fuel that cannot be ignited will be sent back to the fuel chamber in the EGR system and your fuel in the form of carbonized sludge will be sent to your ignition system (this is not only the spark plug, It will easily bring along many malfunctions such as the entire ignition system, combustion chamber, failure of the coils).
Although such systems are made to protect nature and air, since they cannot distinguish full gases, they cause very high costs to vehicle owners and prevent the vehicle from using its full power.
For this reason, it is generally recommended to disable EGR systems (without removing the mechanical egr part) through your vehicles software and are disabled in many vehicles.