2000 silverado Z71 horrible gas mileage
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I would try replacing the 2 pre-cat O2 sensors, they often get lazy in older vehicles and will stick a little lean causing the PCM to add more fuel than required. The trucks are well known for having problems with the O2 sensors. If they go totally dead they'll throw the check engine light on, but if they're just starting to act up they may not until the parameters hit the threshold of throwing a code.
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phwe9774
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04-15-2014 02:57 PM
Spl170s
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05-08-2008 06:43 PM