VGT(Variable Geometric Turbocharger) is the device which increases the efficiency of turbocharger at low rpm and lasts optimum turbo efficiency at high rpm as varying the cross sectional area through which exhaust gas passes turbocharger impeller. It relieves turbo lag at low speed and increse engine power generation.
Engine speed, APS signal, MAFS and Boost pressure sensor information is inputted to ECM.
ECM actuates vacuum diafragm which controls exhaust gas line as controlling VGT Control solenoid valve duty to maintain optimum state of air compression.
P0234 is set when real boost pressure is much higher than target boost pressure for more than 12 sec. at above 1750RPM and 22mg/hub of fuel injection quantity. This code is due to poor connection of VGT solenoid valve vacuum hose, vacuum leakage, clogging, VGT turbo charger component failure.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Signal monitoring
? VGT solenoid component
? VGT vacuum line
? VGT turbo charger component
Enable Conditions
? Engine running(at above 1750RPM and 22mg/hub of fuel injection quantity)
Threshold Value
? Real boost press. is much higher than target boost press.
Diagnostic Time
? 12 sec.
Fail Safe
Fuel Cut
NO
EGR Off
YES
Fuel Limit
Check Lamp
VGT Actuator Component Resistance
VGT Actuator Operating Hz
VGT Actuator Operating Duty
14.7 ~ 16.1O (20?)
300Hz
76% at idle, decreases as accelerating