You can use the Preflight tool to fix many errors in a document. To do this, you add error corrections, called fixups, to a profile. The fixup automatically corrects the problem, if possible, or provides information so that you can correct the problem in the source file. A profile with a fixup has the gray wrench icon next to it. An outline of a wrench means that no fixups are associated with the profile.
Preflight includes several predefined fixups that you can add to a profile. These cover a broad range of errors that affect color, fonts, images, print production, compliance with international standards like PDF/X and PDF/A, and other areas. Preflight also includes a toolkit for creating your own single fixups.
Note:
A fixup permanently changes the document.
Convert color spaces, just as the Convert Color feature does.
Repair documents and eliminate unneeded content to reduce file size, just as PDF Optimizer does.
Convert the PDF to a different version.
Widen hairlines.
Flatten transparency.
Remove objects outside the trim and bleed boxes.
Prepare the PDF for PDF/X, PDF/E, or PDF/A conversions.
Set document information.
The Preflight tool includes a collection of fixups that you can add to a profile. These are all available from the Fixups section of each profile.
TheEdit Fixup dialog box lists the types of predefined fixups you can add to a profile, and the values associated with each fixup. You can use the Edit Fixup dialog box to change the values associated with a fixup, or create a custom fixup based on an existing one. Like checks, fixups are organized by categories.

A. Fixup name B. Fixup categories C. Fixup criteria D. Button for seeing which profiles use the fixup E. Search F. Areas in the fixup that can be modified
You can create a custom fixup for certain jobs or output devices. The settings you specify determine such things as what output intent is used, what color conversions take place, how images are compressed and sampled, and what PDF compatibility level the PDF must support. Although you can modify any of the predefined fixups, as long as they are unlocked, it is better to duplicate an existing fixup and change its values. This technique is useful if the fixup belongs to multiple locked profiles, and you don’t want to find and unlock all those profiles. A duplicated fixup is unlocked by default because it does not yet belong to a profile. You can also create a single fixup that can be quickly run without it being part of a profile.