Is your check engine light on? Here are some tips to help determine the possible cause. It is possible that the emission system could have an issue. The emission system includes oxygen sensors, three way catalyst and catalytic convertor. If there is a problem with one of the above mentioned systems, is could result in increased fuel consumption, higher vehicle emissions and cause you to fail a state or local vehicle emissions testing. Check to make sure the gas cap is secure or for loose or damaged wires connecting to the oxygen sensor. A professional diagnostic scan may be required, which could result in needing a new oxygen sensor.