The wire of the temperature sensor is disconnected.

1. Check if the wire (reference 1 of image) of the temperature sensor is plugged into its socket.

2. Check if the wire (reference 2 of image) is plugged into its socket on the Signal Backplane.

The wire of the temperature sensor is damaged.

1. Repair the wire of the temperature sensor which measures the heat sink temperature of the Light Pipe (reference 3 image)

2. If not repairable, replace the temperature sensor.

Defect temperature sensor.

Replace the temperature sensor which measures the heat sink temperature of the Light Pipe (reference 3 ) .

Malfunction on the Cinema Control board.

Replace the Cinema Control board. See service manual chapter "Replacement of the Cinema Controller".