AS-4000 User’s Guide Maintenance If the spectrum sensor module is dirty, it must be cleaned otherwise a self-diagnosis error will occur. Cleaning procedure A Turn off the press. B Open the cover of the color measurement unit. 87 Item Setting Contents Frequency Clean when a self-diagnosis error occurs. Time required Approx. 5 minutes Maintenance products to use ❏ Polyester/nylon knit woven fabric ❏ Air spray