What is the Front section - M7042 - upper cover front positioning cylinder - extension (front) error?

What is the abnormal extension observed in this error?

What is the machine code of KM-ASSYH2-04 associated with this error?
The solution for the error described as Front section - M7042 - upper cover front positioning cylinder - extension (front), extension is abnormal, please check sensor X45, is to inspect sensor X45 for proper function