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What Can Make Your Car Fail an Emissions Test?

Brian Bates

Emission Testing

If you didn’t know already, fuel powered vehicles can emit various toxic gasses from combustion in the engine. Once it gets released into the atmosphere, it can cause a lot of harmful environmental impacts. Fortunately, our government requires most drivers to get emissions tests to ensure these gasses are released at a safer limit. This ensures that our air quality doesn’t completely deteriorate. 


In Littleton, Colorado, you are required to take your vehicle to a licensed testing station for your emissions test. In order for your vehicle to be legally registered, you will need to pass the emissions test.  


If you’re wondering what can cause your vehicle to fail an emissions test, read on to learn more.


Check Engine Light On

An illuminated check engine light will result in immediate failure. If this yellow warning light is on your dash, please make sure you have it diagnosed and repaired before your emissions test. 


Leaky Fuel Cap

If gas cap seals are worn and allow the fumes to escape, the vehicle will fail the smog test. 


Evap Control System Issue

The evaporative emission control system (EVAP) consists of many hoses, lines, seals, and vents that can also leak gas over time. Make sure they are all in good shape.


Bad Catalytic Converter, O2 Sensor, or Fuel Injectors

​When any of these parts malfunction, it can lead to excess contaminants or too rich of an air-fuel mixture out the tailpipe. 


What Happens When My Car Fails Emissions

If your car fails emissions, you should not stress. Your technician will let you know exactly what went wrong. Additionally, we will give you recommendations on what repairs need to be made to make your vehicle pass. For the most part, emissions repairs aren’t that big of a deal.


You can always count on the emissions experts at EAS Tire & Auto for accurate and convenient emissions testing. If you need a smog test in Littleton, CO, please give us a call or visit soon.

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