Could be a bad motor or a broken harness wire between the motor and board. There is a tachometer, called a Hall Sensor, which provides input back to the board. If the RPMs are not up to par or the Hall sensor, the motor is bad, the error code comes up. All this code means is that the motor is not at the expected RPMs. It's up to you to find out which is bad. The manual gives you the OHM readings for all the motor contacts, etc., so unless you are electronically-challenged this should be an easy diagnosis.
According to the tech sheet, the E48 code directly points to an open motor phase. If the motor OHMs out correctly, replace the inverter.