Lens is touching the sensor on the prism. Maximum lens shift position reached.

Shift the lens upwards and/or to the left.

Defect prism sensor.

Remove lens and reboot projector, if warning appears again then the prism sensor is defective and needs to be replaced (reference 1 of image).

Caution: after replacement of the prism sensor ensure that the wire of the prism sensor is connected with the Signal Backplane! (reference 2 of image and reference 5 of image)