What does it mean when your car says "check emission system?"

When your vehicle displays a message to "Check emission system", the car’s computer is telling you that one or more of the emission control systems is not working properly. This could be something as simple as a loose or faulty fuel cap, or something more costly and complicated, like a bad catalytic converter. If an emission system issue is left unchecked, it will likely result in poor fuel mileage, failure of emissions testing, and could damage any number of vehicle components.

Can I drive with an emission system problem?

Whether or not you can safely drive with an emission system problem depends on exactly what the problem is. Or on what is causing the emission system light on your dashboard to turn on. If the problem is minor, such as a loose gas cap, driveability will likely be unaffected (although you might see a check engine light and lose some fuel efficiency). But if the problem is more significant, a bad EGR valve for example, your engine could develop a spark knock during acceleration and incur serious damage. It is best to have your vehicle checked by a qualified professional if you suspect an emission system fault of any kind.

What causes emission system problems?

Emission system problems are caused by a number of factors. These include engine misfiring, unburnt fuel coming through the exhaust system, excessive corrosion causing pressure or vacuum leaks, and simply high mileage that leads to component failure.