Why is the check

Nov 27, 2023

I have a 2014 Buick LaCrosse with 35,000 km. A check-engine light comes on after a fill-up, then goes away a few days later depending how many times I drive. Next fill-up, same problem. I make sure the gas cap is on tight.– B.M.

If you were to have this vehicle's computer scanned, I am confident that a P0442, EVAP emissions small-leak code would be stored.

The evaporative emission control system (EVAP) is present in all 1996-and-newer vehicles and is designed to keep gasoline vapour from escaping.

It does this with a series of solenoids, valves and a vapor-storage canister.

Your on-board computer is constantly monitoring the system as you drive and will illuminate a "check gas cap" loose indicator or engine malfunction light when the slightest leak is detected.

The most obvious starting point is at the gas cap.

Check the mating surface at the filler neck for corrosion or debris which may be preventing a good seal, or replace the gas cap entirely.

Further, there is a part known as a purge solenoid valve which I suspect is the likely culprit, as it is known to fail on this model.

Left unchecked, this solenoid will eventually cause a difficulty to start condition after every fill-up.

Given the year and mileage of your vehicle, you may still have warranty coverage for this piece.

Lou Trottier is owner-operator of All About Imports in Mississauga.

Have a question about maintenance and repair? E-mail [email protected], placing "Lou's Garage" in the subject area.