Why am I getting an Apple Hardware Error 4MOT/1/40000003:HDD-1364

If it starts with 4MOT it's a motor (fan) error

If it ends in HDD it relates to the HDD fan, The number at the end is the actual rpm for the fan.

This error is generated if the actual fan speed is outside the +/- 10% allowance for the target speed. So you likely have a failing fan nearest the HDD

I'd be sure to backup any PITA data on the HDD, as it may be/have been acting up (overheating) which is caus(ed)ing the fan to fail.

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