KIA RIO TIRITA MANUBRIO

Hello, I have a Kia Rio 4 2013 with 93000km, for a couple of weeks I began to shiver the handlebar, being detained, when the steering wheel is not vibration, but when the steering wheel is released and in the right position the vibration feels, I went to an attorney, a mechanic indicated that it is the direction engine and that it is expensive, I need some other suggestion and know if it really is that.
The vehicle is electronic servosistid.