Indicates the optic is operating in a high-temperature environment. If temperature remains high after improving airflow → relocate optic or replace if thermal issues persist. Clear and re-read alarms/DOM; verify link state on both ends. However, common causes of optical module failures, such as ESD (electrostatic discharge). This guide provides a deep technical overview of how to troubleshoot sfp optical transceivers and other optical transceivers module types effectively in 2025. If so, this fault is typically caused by high insertion loss of the connector or the bending of the optical fiber.