what is egr flow malfunction?
<answer> At high combustion temperatures, the Nitrogen in the air can combine with the air fuel mixture to produce Oxides of Nitrogen–a key component of smog. <context> Fix code P0400 Exhaust Gas Recirculation Flow Malfunction. EGR stands for Exhaust Gas Recirculation. At high combustion temperatures, the Nitrogen in the air can combine with the air fuel mixture to produce Oxides of Nitrogen–a key component of smog.