Tip & How-To about Buick LeSabre
This can happen if the gas cap is not properly installed. Make sure you hear several clicks when installing. After 10 or so starts the Service Engine Soon light usually goes away.
A second cause could be a problem with the ground wire that comes from the gas cap sensor and goes to the body. Look up into the wheel well by the filler pipe to check.
A third can be the result of a vacuum leak in the fuel evaporator (EVAP) system. Look for any hoses that go from the air intake to a sensor on the fuel rail (fuel injected cars). Many cars have plastic engine covers that have to be removed to see the fuel rails, sensors and hoses. Most require unscrewing the oil filler to get the cover off. You may not think the hose is leaking but replacing may make your problem go away. A small vacuum leak can also affect the fuel flow and affect the engine operation.
My experience is with the 3.8 engine but this probably applies to lots of engines. On the 3.8 it is the two piece hose that comes from the air intake with one small hose going to the top of the engine and the other going across the front of the engine into a hose that does a 180 degree turn that comes back to a sensor. It costs about $25 and is a dealer item.
There may be other causes but these are three common ones.
Posted by FHyslopJr on
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