DIESEL CONTROL SYSTEM
DTC P0489 EXHAUST GAS RECIRCULATION CONTROL CIRCUIT LOW
Electric EGR control valve
Receiving ECM signal, linear solenoid type electronic EGR actuator operates Electric EGR control valve directly.ECM
performs EGR system feed back control with the information of measured mass air flow (The role of MAFS in diesel
engine is different from gasoline engine. Fuel injection quantity is decided by MAFS signal in gasoline engine.)When EGR
gas(contains no oxygen) flowing into combustion chamber increases, the air passing through MAFS(contains oxygen)
decreases. Thus, with the output signal change of MAFS accompanied by Electric EGR control valve actuation, ECM
determine the amount of recirculated EGR gas quantity.
NOx is produced from the reaction of nitrogen and oxygen. Controlling EGR gas(contains no oxyger) which is recir-
culated to combustion chamber, if least intake air required for complete combustion flows into combustion chamber,
NOx decreases because there is no supplementary oxygen to react with nitrogen.