Based on my experience with a 98 E320 and other posts regarding E320's, a check engine electronics message usually has been the cause of a mass air flow sensor going bad.

But as Gilly as suggested get the codes to verify the cause of the check electronics message.

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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles