Royal pain if the MAF happens to throw a CEL just before a required emissions test. Potentially some diagnostic time to sort out the CEL only to finally end up being a simple-to-change MAF. In that case, the preventative maintenace theory might make a lot of sense.

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ARVY

1999 E430
1999 C230 Kompressor
1992 300E (write-off)
1984 190D 2.2 (sold)