check engine light on 2004 Chevrolet Impala

car has 67K miles. CEL went on last week. Had the code checked. Was told it could be the fuel injectors need cleaning. Put in Lucas fuel inj cleaner with full tank of gas. When should light go off? Or do I need to reset it? code reader read: too lean mixture (bank 1). Could there be another issue also??

by in Addison, IL on September 23, 2010
1 answer 1 comment
ANSWER by on September 23, 2010
I presume the fuel trim figures showed the computer was adding fuel causing a lean code to be set. A lean code could be set if the fuel pressure or delivery is low (failing fuel pump) or if there is a vacuum leak allowing air that the air flow meter doesn't see to enter the engine, another possible cause is an air flow meter that is failing and not sending a correct signal to the computer in your car so it can calculate how much fuel to inject into the engine. More diagnosis may be needed. The Check Engine Light can be reset with a scan tool or will reset after a series of drive cycles are done and the computer no longer sees a problem.
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COMMENT by on September 23, 2010
Thank you for your answer, Patrick. I am trying to figure this out as best I can on my own, before I take it to a garage and they assume I'm completely clueless. How can I be sure what is ultimately causing the problem without replacing the fuel pump, or vacuum leak, etc.... Thank you!
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