I have a 2001 Buick LaSabre with a check engine light and code reading of 440 (Evaporative emission control system malfunction). any ideas what the main problem could be? The car was just tuned up with new plugs, wires, filters including fuel and air, pcv valve Etc. it runs like a top but I had noticed the fuel mileage had dropped to 21 MPG from 32 MPG before I had it tuned up and that has not improved and the code is comming back
It could be as simple as a bad gas cap.
I’m a bit perplexed about your fuel economy claim. 32 MPG sounds awfully high for this vehicle.
It’s a 3.8 liter engine, I have had great gas mileage with that engine. before this car I had a 1993 olds 88 with the same engine that got 35 MPG that is the reason I wanted to stay with it besides it is an easy engine to do regular maint. oil changes on since I still like to do them myself.
Then there must be something seriously wrong with he evaporative emissions system to cause such a dramatic drop in fuel economy. Are you getting any puddles of gas or a strong gasoline smell from the car?
No, none what so ever