I have a 2001 S430 with Check Engine Light on almost every other days ,then self cleared after some drive cycles. Finally bought an OBD scanner for Mercedes S & E class, get two error codes (P2017 & P2086) from scanner.
Can someone help me advises as to how this problem?

Those codes means that the computer has made ALL of the adjustments that it can, either lean or rich.

MOST of the time IF you had "live" data available from your scanner you would see a LEAN mixture. Lean mixture adaptation comes from low fuel pressure, vacuum leaks, & MOST commonly a bad air mass sensor(MAS or MAF)

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CEL gone after MAF replaced. Thanks,"M.B.DOC.".