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 AFS in diesel engine is different from gasoline engine. Fuel injection quantity is decided by AFS 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 EEGR actuator actuation, ECM determines the amount of recirculated EGR gas quantity.
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.
P0401 is set when EGR governer deviaton is below the lower limit value for more than 4 sec.. This code is due to open or short to ground in EEGR actuator circuit or internal open 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 GND, wiring open
Diagnostic Time
? 4 sec.
Fail Safe
Fuel Cut
NO
EGR Off
YES
Fuel Limit
Check Lamp
EGR actuator component resistance
EGR actuator operating Hz
EGR actuator operating duty
7.3~ 8.8O (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.