This article explains why the chassis on ACX6360-OX may raise intermittent I2C Access Error alarms against FRUs (field replaceable units), including Fan and PEM, and whether any action must be taken to clear the alarms.
The following alarms will toggle and clear autonomously:
Feb 26 00:50:13 [nodename] alarmd[7113]: Alarm set: FAN color=RED, class=CHASSIS, reason=Fan Tray 3 I2C Access Error Feb 26 00:50:13 [nodename] alarmd[7113]: Alarm cleared: FAN color=RED, class=CHASSIS, reason=Fan Tray 3 I2C Access Error .. Feb 27 18:46:54 [nodename] craftd[7114]: Major alarm set, PEM 1 I2C Failure Feb 27 18:46:54 [nodename] alarmd[7113]: Alarm cleared: PS SFXPC color=RED, class=CHASSIS, reason=PEM 1 I2C Failure
The firmware version query mechanism was revised in Junos OS release 18.3R1-S1 and later to avoid I2C collisions, which eliminates the conflict and alarms.
Meanwhile, no action is required because the condition is cleared autonomously and does not affect any service.