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

Problem Description and Possible Solution

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

Problem Data
RepairPal Verified
Average mileage: 107,166 (55,000–160,000)
5 model years affected: 1998, 1999, 2001, 2004, more2005
13 people reported this problem
Viewing 1 - 5 of 5 comments
check engine light on ... going to put new catalytic converter on Friday will let u know if it fixes th problem
Check engine light comes on, check gas cap warning. Mine is caused by a rotted gas overflow line. Seems that it has rotted so bad that when I top off the gas tank, it started overflowing to the ground. It is also causing a miss in my engine when accelerating (not getting full power due to fuel pressure). Have not repaired yet but have found the fuel filler neck on eBay for $70.00. I was told you can cut off the bad section of the overflow, and clamp on a 3/4 ID fuel line. I am certain this would work, however if the line is that rotted I think I will install a new one for the $70 price.
check engine light comes on when gas reading reaches 8, 10 and 11 gals. Had new catalytic converter put on also o2 sensor thought everything would be alright, but when gas reading came down to 11 gals. check engine light came on again, had it check by computer and got the same reading as befor bad 02 sensor.
Intermittant engine light due to gas filler cap. Replaced cap, but intermittant problems persists. No fix yet.