Receiving ECM signal, DC motor type EGR actuator operates EGR 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 EGR actuator actuation, ECM determine the amount of recirculated EGR gas uantity.
NOx is produced from the reaction of nitrogen and oxygen. Controlling EGR gas (contains no oxygen) 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 EGR actuator motor circuit is short to battery more than 1 sec. Check the both of motor (+) and (-).
Item | Detecting Condition | Possible Cause | ||
DTC Strategy |
•
Voltage Monitoring |
•
EGR actuator motor | ||
Enable Conditions |
•
Engine running | |||
Threshold value |
•
EGR actuator moter circuit is short to battery | |||
Diagnosis Time |
•
1000ms | |||
Fail Safe | Fuel cut | NO |
•
- | |
EGR Off | YES | |||
Fuel Limit | YES | |||
Check Lamp | ON | |||
EGR actuatior resistance | EGR actuator frequency | EGR acturator duty | |
Motor | 6~170Ω (terminal 1-3) | 1000 Hz | 0 ~ 100 % |
Position sensor | 172Ω (terminal 5-6) | - | - |
116Ω (terminal 4-5) | - | - | |
161Ω (terminal 4-6) | - | - |
Fig 1) EGR actuator motor(-) is controlled at idle or deceleration
Fig 2) EGR actuator motor(+) is controlled at acceleration
