I was under the impression that the check engine light will illuminate only if a fault code has been tripped that affects smog emissions. At least it works this way on my car, but it is OBD-I.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".