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DTC P0401 EGR FUNCTION
EC-1073
[YD (WITH EURO-OBD)]
C
D
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A
EC
DTC P0401 EGR FUNCTION PFP:14710
Description EBS011OS
SYSTEM DESCRIPTION
*: These signals are sent to the ECM through CAN communication line.
This system controls flow rate of EGR led from exhaust manifold to intake manifold. The opening of the EGR
by-pass passage in the EGR volume control valve changes to control the flow rate. A built-in step motor
moves the valve in steps corresponding to the ECM output pulses. The opening of the valve varies for opti-
mum engine control. The optimum value stored in the ECM is determined by considering various engine con-
ditions.
The EGR volume control valve remains close under the following conditions.
● Engine stopped
● Engine starting
● Low engine coolant temperature
● High engine speed
● Accelerator pedal fully depressed
COMPONENT DESCRIPTION
EGR Volume Control Valve
The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the ECM.
Two windings are turned ON and OFF in sequence. Each time an
ON pulse is issued, the valve opens or closes, changing the flow
rate. When no change in the flow rate is needed, the ECM does not
issue the pulse signal. A certain voltage signal is issued so that the
valve remains at that particular opening.
Sensor Input Signal to ECM ECM Function Actuator
Crankshaft position sensor Engine speed
EGR volume con-
trol
EGR volume control
valve
Vehicle speed sensor* Vehicle speed
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Accelerator pedal position sensor Accelerator pedal position
Mass air flow sensor Amount of intake air
Air conditioner switch
*
Air conditioner operation
SEF908Y
SEF411Y
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