Dell PowerEdge R420 Systems Owner's Manual

For faults associated with sensors, such as temperature, voltage, fans, and so on, the LCD message is automatically removed when that sensor returns to a normal state. For other faults, you must take action to remove the message from the display:

• Clear the SEL — You can perform this task remotely, but you will lose the event history for the system.
• Power cycle — Turn off the system and disconnect it from the electrical outlet; wait approximately 10 seconds, reconnect the power cable, and restart the system.