Er2 is a code for "no sensor counts" There are different causes for that. If the dish is froze up and the motor doesn't have the power to move it then after 1/2 second of getting the signal to move it sees no sensor count and stops and displays that er2. If the sensor or wiring is damaged, Er2. Check your sensor connections.
If the motor wiring is open circuit then you will get that code. If the motor wiring is shorted you will get Er1