A faulty coil may or may not result in a code on the M104. From my experience, a defective coil that causes rough running at idle, and/or miss under acceleration will not result in a stored code.......

J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles