2003 Buick LeSabre check engine light


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Old 09-03-16, 11:19 AM
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2003 Buick LeSabre check engine light

Every time I fill up my tank or my gas runs low I run into the same Evap Code issue as a check engine light.

Between the 3/4 tank and 1/8 tank, the lights gone and I haven't had a single problem in the performance. But Smog time is coming, and I know this light is gonna show up on the reader.

Any ideas?
 
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Old 09-03-16, 11:28 AM
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Welcome to the forums.

You need to see what codes are set into memory and then work towards repairing them.
 
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Old 09-03-16, 11:36 AM
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P0440 and every time I look it up all I find from people is that I should replace the gas cap. I have replaced it several times, including one from GM and high performance and the current AC Delco on it.
 
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Old 09-03-16, 12:19 PM
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P0440 = Evaporative System Malfunction, Large Leak

When your vehicle is started there is a vacuum placed on the fuel vapor recovery system which includes the fuel tank for ten seconds. Then the vacuum valve is closed and a sensor monitors how fast the vacuum in the system decays or is lost. If it's too fast it knows there is a large leak and alerts you with a P0440 code. This test is only performed when the fuel level is between 15% - 85% of full.

The gas cap is only one cause of the problem. If you've replaced the cap.... that is not the problem.

With the age of your vehicle I'd guess you have a cracked or broken vacuum hose.
Another possible cause is a crack in the fill line or the vent line on the filler neck.
 
 

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