Damaged insulation of the wire unit of the temperature sensor (reference 1 image "Light pipe temperature sensor connection") which measures the temperature of the water cooling block of the light pipe entrance. When disconnecting the wire unit (reference 3 image "Light pipe temperature sensor connection") of the temperature sensor from the Formatting Interface Board the error code is changed to “light pipe - temperature sensor open”.

1. Repair the insulation of the wire unit using shrink sleeve.

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

Defect temperature sensor on the water cooling block of the light pipe entrance. When disconnecting the wire unit (reference 1 image "Light pipe temperature sensor connection") of the temperature sensor from the Signal backplane, the error code is changed to “light pipe - temperature sensor open”.

Replace the temperature sensor.

Malfunction Fan Control board.

Replace the Fan Control board. See "Removing a board in the card cage".