COMPONENT LOCATION
GENERAL DESCRIPTION
Linear solenoid type electronic EGR actuator operates EGR valve directly throuth ECM control.ECM perform feed back control of EGR system using measured intake air quantity information.(this mechanism is different from gasoline engine's which controls fuel injection quantity according to intake air quantity.) Air quantity to engine cylinders(the air contains oxygen) via MAFS decreases when EGR gas (the air does not contain oxygen) flows in combustion chambers by EGR actuator operation. It can be said briefly that recirculated EGR gas quantity is detected through the change of output voltage of MAFS according to EGR actuator operation.
noteNOx is made from the chemical reaction between nitrogen and oxygen. The least intake air needed in complete combustion of fuel flows in combustion chamber as controlling EGR gas(the air does not contain oxygen) which is recirculate to combustion chamber. Through this process, NOx decreases as the oxygen reactable with nitrogen does not exist.
DTC DESCRIPTION
P0402 is set when actual intake air quantity sensed at MAFS is less than target intake air quantity. Check if the reason of insufficiency of actual air quantity is due to MAFS or excessive operation of EGR valve.
DTC DETECTING CONDITION
Item | Detecting Condition | Possible Cause |
DTC Strategy | Voltage monitoring
| MAFS component EGR actuator component EGR vacuum hose
|
Enable Conditions | Engine running
|
Threshold Value | Intake air quantity calculate based on intake pressure and IAT is below 368mg/st
|
Diagnostic Time | 10 sec. Immediately
|
Fail Safe | Fuel Cut | NO | |
EGR Off | YES |
Fuel Limit | YES |
MIL | YES |
MONITOR SCANTOOL DATA
Connect scantool to Data Link Cable (DLC)
Warm engine up to normal operating temperature.
Turn "OFF" electrical devices and A/C.
Monitor "MAFS " parameter on the scantool.
?EGR actuator operates as decelerating after rapid acceleration when idle EGR does not operate, EGR actuator operating duty decreases as time goes by. This controlling process lasts for about 90sec. and EGR actuator turns "OFF"(duty 5.0%) after 90sec.
COMPONENT INSPECTION
Check EGR actuator component resistance
Ignition "OFF", Turn engine "OFF".
Disconnect EGR actuator (C345)
Measure the resistance between EGR actuator component terminal 1 and 2
Is the measured resistance of EGR actuator component within the specification?
? Go to "2.Check MAFS output signal" as follows.
? Replace EGR actuator and go to "Verification of Vehicle Repair"
Check MAFS output signal
Ignition "OFF", Turn Engine "OFF".
Check that MAFS is installed in correctly according to the direction of arrow on MAFS ASSY'
Check contamination of air cleaner filter.
Ignition "ON", Turn Engine "ON"
Let IDLE RPM last after warming engine up.
Check the leakage of intake system (the leakage of damage of intercooler hose)
Check that EGR actuator does not operate.
( EGR actuator turns "OFF" after 90 sec's acceleration and disconnect EGR actuator connector if needed. )
Monitor output voltage of MAFS when engine speed lasts at 750±50 RPM.
Is output value within the specification?
? Go to "Verification of Vehicle Repair"
? Replace MAFS ASSY' and go to "Verification of Vehicle Repair"
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault is corrected.
After connecting scantool select "Diagnostic Trouble Codes(DTCs)" mode to and then clear DTC.
Drive the vehicle within DTC Enable conditions in General information.
After selecting "Diagnostic Trouble Codes(DTCs)" mode and check DTC is recorded again.
Are any DTCs recorded ?
? Go to the DTC guide of recorded No. in scantool.
? System operates within specification.
SCHEMATIC DIAGRAM