The brew group is not moving properly due to damaged piston gaskets. Check the gaskets and replace them if necessary. Also, the brew group may need to be lubricated.
The error may occur due to a faulty encoder, which is located on the gear motor. The encoder gets a signal from the power board to activate the gear motor, which in turn regulates the positioning of the brew group. Please, make sure the encoder cable is all right. If not, replace it.
The code may also appear when the gear motor of the brew group stops moving. The machine will produce characteristic clicking sounds. Most likely, the PCB or transformer (a unit that regulates alternating current’s voltage) are faulty and need to be replaced.
Finally, it may indicate a defective gear motor. If that is the case, the motor will produce a strange buzzing noise. Most likely, the motor needs to be replaced.