Top four reasons why your check engine light is illuminated.

There are many, many reasons that the check engine light may come on in you car, truck or SUV. A malfunctioning sensor, low tire pressure, low transmission fluid and so much more will cause the light to come on. But some reasons the check engine light comes on are much more common. When the light glows it doesn't always foreshadow an expensive repair, sometimes the issue can be fixed with just the turn of a wrist. Here are 4 common reasons the check engine light is on, and for proper diagnosis be sure to visit your local auto mechanic.

Gas cap is loose, damaged or missing

 

1.  Fuel Cap
   
   
   Your fuel cap seals the fuel system and helps maintain pressure within the fuel tank. It also prevents gasoline fumes (hydrocarbons) from being released into the atmosphere while you aren't driving your car.
   
   

   What if I don't replace it?

   • You can lose fuel through evaporation
   •  You may make more trips to the filling station

   
   
   

2. Air Flow Meter/Mass Airflow Sensor needs replacing

   

   Your air flow meter measures the amount of air entering the engine to determine how much fuel is needed to run your engine efficiently.
   What if I don't replace it?

   • Faulty sensors can cause damage to spark plugs, oxygen sensors or catalytic converter
   • You will experience reduced performance and fuel economy

3. Your Oxygen (O2) Sensor needs replacing

   
   Your oxygen sesor measures the amount of unburned oxygen in your vehicle's exhaust system.
   

   What if I don't replace it?

   • Your engine will burn more fuel than needed
   • You will experience loss of fuel economy (up to 40% if ignored)*
   • Faulty sensor(s) can cause damage to your spark plugs and catalytic converter

4. Spark Plugs or Plug Wires need replacing

   
   
   
   Your spark plugs ignite the air/fuel mixture in the combustion chamber of your vehicle. The spark plug wires deliver the spark from the ignition coil to the spark plugs.
   

   What if I don't replace it?

   • You will experience poor performance (reduced power, engine missing) and reduced fuel economy
   • Worn plugs and plug wires can cause clogged catalytic converter or damage to ignition coils and O2 sensors