On vehicles with PR codes (MG4) And (MF8) CDI system via CDI control unit (N3/9) and vacuum converter (Y31/5) controls the EGR valve (Y27), which regulates the addition (pre-cooled) EG into the engine intake tract in order to reduce the combustion temperature of the fuel. Thus, the EGR system reduces the amount of nitrogen oxides in the exhaust gas (NOx).
The exhaust gases pass through the exhaust gas catalytic converter.