EPS (MDPS=Motor Driving Power Steering) is designed to provide directional control and smooth feeling to driver when driver operates steering wheel. There is a function to detect rotation speed and direction of steering wheel in Torque Sensor. Rotation speed and direction signals are used for "damper" and "return" control, "assist" control.

Steering angle sensor error can be set when loss of steering angle due to internal fault or open in ECU internal circuit occurs. If steering sensor error occurs EPS ECU stops "damper" and "return" control. Therefore driver can be uncomfortable due to no return force during U-Turn, high speed driving, but there is no problem for driving because basic assist control still alives.