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 increase engine power generation.

Engine speed, APS signal, MAFS and Boost pressure sensor information is inputted to ECM.

ECM actuates vacuum diaphragm which controls exhaust gas line as controlling VGT Control solenoid valve duty to maintain optimum state of air compression.

P0048 is set when excessive current is detected in VGT Control solenoid valve control circuit for more than 1 sec.. This code is due to short to battery in control circuit or internal short of VGT Control solenoid valve component.

Fig.1) VGT Control solenoid valve output waveform at 79% duty. Duty decreases as boost pressure increases.

Fig.2) VGT Control solenoid valve duty decreased at acceleration.