Check Engine Light Due to Gas Cap or Catalytic Converter on Cadillac DeVille

Two likely causes for the Check Engine Light to illuminate would be a loose or worn gas cap or a faulty catalytic converter.

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Average mileage: 160,000 (160,000–160,000)
1 model year affected: 1998
2 people reported this problem
1 person shared problem details
1998 Cadillac DeVille160,000
I keep getting MIl Code P0440, and have repaired everything in evap system w/o curing this problem.
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Illumination of the Check Engine Light can be caused by a loose or worn gas cap.
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