Receiving ECM signal, linear solenoid type electronic EGR actuator operates EEGR 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 EEGR actuator 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 EEGR actuator circuit for more than 0.5 sec.. This code is due to short to battery in EEGR actuator control circuit or internal short in EEGR component.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy | ● Signal monitoring | ● EGR actuator circuit ● EGR actuator component | ||
Enable Conditions | ● Engine running | |||
Threshold Value | ● Short to battery | |||
Diagnostic Time | ● 0.5 sec. | |||
Fail Safe | Fuel Cut | NO | ||
EGR Off | YES | |||
Fuel Limit | NO | |||
MIL | OFF |
EGR actuator component resistance | EGR actuator operating Hz | EGR actuator operating duty |
7.3~ 8.8Ω (30℃) | 142Hz | approx.10%(closed)~40%(opened) |
The output of approx. 10% duty is mainly for the diagnosis of EEGR actuator circuit than actuating EEGR.