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Old 10-30-2007, 08:41 PM   #14
ChevyTech
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Join Date: May 2004
Location: Minnesota
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Re: Code #41 and #55

High vacuum is not bad, but the system is most likely sensing a reading that it determines to be in error (to high to believe for the other existing criteria), like if you had a hand vacuum pump on the MAP sensor and pump vacuum under open throttle conditions when it expects to see low vacuum.
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