2009 Chevrolet Cobalt Causing Decreasing Fuel Mileage Xfe Proper Tire Pressure

2009 CHEVROLET COBALT
30 MILES
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STUDEBAKER437
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  • 1 POST
what is causing decreasing fuel mileage in my xfe? I have proper tire pressure, clean air filter, and new spark plugs. could it be an oxygen sensor or catalytic convertor clogging?
Jan 8, 2012 at 11:32 PM
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MHPAUTOS
  • ✓ASE Certified Mechanic
  • 31,937 POSTS
  • ASE Certified Mechanic
Check that the O2 sensor is working correctly, these can go out of calibration and send mixtures rich over a period of time, if it has never been replaced i would consider doing so, also a scan for any unresolved fault codes, start here.
Jan 9, 2012 at 12:19 AM
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