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.
P0490 is set when excessive current is detected in Electric EGR control valve circuit for more than 0.5 sec.. This code is due to short to battery in Electric EGR control valve control circuit or internal short in Electric EGR control valve component.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy | ● Signal monitoring | ● Electric EGR control valve circuit ● Electric EGR control valve component | ||
Enable Conditions | ● Engine run | |||
Threshold Value | ● Short to battery | |||
Diagnostic Time | ● 500ms | |||
Fail Safe | Fuel Cut | NO | ||
EGR Off | YES | |||
Fuel Limit | NO | |||
Check Lamp | NO | |||
Electric EGR control valve component resistance | Electric EGR control valve operating Hz | Electric EGR control valve operating duty |
14.7 ~ 16.1Ω (20℃) | 142Hz | 5%(closed)~39%(opened) |
The output of approx. 6% duty is mainly for the diagnosis of Electric EGR control valve circuit than actuating EEGR.
