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O2 sensor

Old Jul 4, 2011 | 10:34 AM
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Default O2 sensor

On my scanner two out of the three o2 sensors the values change rapidly. They are up and down while idling and driving

They are very inconsistent they range from .100 to .800. I'm guessing this isn't normal
 
Old Jul 4, 2011 | 12:28 PM
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Perfectly normal for the upstream sensors to change rapidly. They react to changes in fuel mixture so the ECM can adjust it accordingly. A low reading .1 indicates a lean mixture and a high reading .9 indicates a rich mixture. They should never indicate above .9 volts. The faster they react to mixture changes, the faster the ECM can adjust injector pulse width and provide better fuel economy. Overall, the voltage should average around .450 volts. The downstream sensor monitors catalyst performance only and should remain relatively steady around .4 volts.
 
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