Hyundai Sonata LF: Engine Control System / RCV Control Solenoid Valve Description and Operation
RCV (Recirculation Valve) Control Solenoid Valve is installed
on the cooling pan motor top and operates the RCV actuator which
controls the by-pass passage of the turbo-charger compressor.
When the throttle valve is closed during engine running
[Tip-out], crash noise of the impeller will occur because of rapid
increasing of the boost pressure. So, in this case, in order to prevent
this phenomenon, ECM maintains the appropriate boost pressure by opening
the by-pass passage.

Inspection
[Motor]
1.
Turn ignition switch OFF.
2.
Disconnect the EWGA connector.
3.
Check that the EWGA is stuck by foreign material.
4...
Other information:
C..
Compession Pressure Inspection
If the there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.
1.
Make sure the oil in the crankcase is of the correct
viscosity and at the correct level and that the battery is correctly
charged...