Most municipalities have regulations on the number of toxic pollutants your vehicle is allowed to emit to keep the air clean so people do not become ill. However, from your car's standpoint, if it emitting too many harmful gases, there is something wrong that needs to be addressed for the efficiency of the vehicle. Here are just a few problems that could cause the auto to fail an emissions test.

Dirty Spark Plugs

If the spark plugs are dirty or worn, they will allow excess gas to flow through the system because it is not being burned properly. Replacing them is a quick and simple task. Not only will it reduce the emissions so the vehicle will pass the test, but you will also notice you are getting better gas mileage. 

Bad Air-Fuel Mixture

When you are told that you have a rich air-fuel mixture, it is time to check the fuel injectors and the oxygen sensor. When these parts are not working correctly, fuel can be pushed through the system instead of being burned in the engine. In most cases, the fuel will not be able to get burned off by the catalytic converter and toxic fumes will blow out of the tailpipe. Not only will this result in a waste of fuel, but you may also notice your vehicle jumping forward when you give it gas. This could potentially cause an accident.

Leaking or Loose Gas Cap

A simple issue is a loose or leaking gas cap. When this happens, extra air will get into the gas lines and create a fuel-air mixture problem. This will often cause the check-engine light to come on too. While this will not cause a problem with the vehicle per se, it may have you checking other parts to find why the light is on and why you failed the test. Always check the gas cap, and if it feels a bit loose, get a new one, as they are not expensive.

Failing an emissions test will keep you from renewing the vehicle's registration. Most of the time it is something simple. Quite often you can take the auto to a shop and have them hook it up to the diagnostic computer for free. It is rare to have the computer not be able to tell you what is wrong. You should be able to get the needed part and correct the issue right then so you can go take the test again.

For more information, get in touch with a company such as H & S Tire & Auto Center.