Wire unit (reference 1 & 3 image) of the temperature sensor is disconnected from the Signal Backplane.

Plug in the wire unit of the temperature sensor into its socket on the Signal Backplane.

Damaged wire unit of the temperature (reference 3 image) sensor which measures the temperature of the water cooling block of the light pipe entrance.

1. Repair the wire unit.

2. If not repairable, replace the whole wire unit and temperature sensor.

Defect temperature sensor (reference 3 image) on the water cooling block of the light pipe entrance.

Replace the temperature sensor.

Malfunction Fan Control board.

Replace the Fan Control board. See "Replacement of a Card Cage board".