What the heck is a EVAP system?

It stands for Evaporative emissions control. It keeps fuel vapors inside you fuel tank from escaping into the environment. 1996 and newer vehicles have a computer that monitors the components of the EVAP system and will set a code that will cause the check engine light to come on if it detects a leak or fault. Leaving your gas cap loose or off will certainly turn on your check engine light. When the cap is secured properly the light will go off again the next time your computer runs a system check on the EVAP.

To TEST or Not TEST... with Check engine light on?

When your check engine light is on, your vehicle will fail the California State Smog Test. However it's recommended that the test be done anyway to help identify other emissions related problems in the other parts of the test. This way the repair station can address all of your vehicles problems at one visit. You won't be going back and forth to your mechanic over and over again.

Whats a "Check Engine Light"

On vehicles with onboard computer controlled engine systems the computer is capable of monitoring various electronic and mechanical components for proper operation. When a fault is detected it sets the check engine light to warn the operator of the fault. Referred to as the MIL (Malfunction Indicator Light) in the business. The light has two modes constant on and flashing. If the light is flashing it means your vehicle has a serious problem and damage may be occurring. If you notice this light is flashing the operator should as soon as safe move the vehicle off the road and shut the engine off and have a certified mechanic look into the problem.

What does the smog check consist of?

The inspection basically has three parts, a comprehensive visual inspection that is done by the Technician, a functional systems check that is partly or solely done by the technician and your car’s computer depending on year, and the tail pipe emissions gas composition analysis that is done by the Smog Station's computer.

This blog was started to help you understand the California State Smog Check program and to offer information about specific emissions related problems. I will answer questions and post remarks and helpful hints you can use to get your vehicle ready for your next Bi-annual smog check.

(Disclaimer) This blog is not intended to offer a diagnosis or recommend a specific repair. It is always best to have your vehicle diagnosed and repaired at an emissions repair station certified to do so by the Ca. State Smog Program.