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.
P0405 is set when EGR actuator position sensor output voltage is less than 133mV for 2.5sec.
Item
Detecting Condition
Possible Cause
DTC Strategy
Signal monitoring
EGR actuator motor position sensor circuit
EGR actuator
Enable Conditions
Engine running
Threshold value
EGR actuator position sensor output voltage is less than 133mV
Diagnosis Time
2.5 sec.
Fail Safe
Fuel cut
NO
-
EGR Off
YES
Fuel Limit
Check Lamp
ON
EGR actuatior resistance
EGR actuator frequency
EGR acturator duty
Motor
23 O (terminal 1-3)
1000 Hz
0 ~ 100 %
Position sensor
6.11 kO (terminal 5-6)
6.03 kO (terminal 4-5)
170.1 O (terminal 4-6)
Fig 1) EGR actuator motor(-) is controlled at idle or deceleration
Fig 2) EGR actuator motor(+) is controlled at acceleration