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 AFS(contains oxygen) decreases. Thus, with the output signal change of AFS 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 recirculated 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.
P0489 is set when '0'A is detected in Electric EGR control valve circuit for more than 0.65 sec.. This code is due to open or short to ground in Electric EGR control valve circuit or internal open in Electric EGR control valve component.
Item
Detecting Condition
Possible Cause
DTC Strategy
Feed back position monitoring
Electric EGR control valve circuit
Electric EGR control valve component
Enable Conditions
IG OFF
Threshold Value
EGR valve feed back position voltage signal < 0.5V
Diagnostic Time
650 msec.
Fail Safe
Fuel cut
NO
EGR Off
Fuel Limit
MIL
YES
Fig.1) Approx. 5% duty signal waveform of Electric EGR control valve (with EEGR valve closed)
Fig.2) Approx. 57% duty signal waveform of Electric EGR control valve(with EEGR valve opened)
The output of approx. 5% duty is mainly for the diagnosis of Electric EGR control valve circuit than actuating EEGR.