We believe the test station staff has gained experience and speed, so the cap check shouldn't cause delays any more. The gas cap inspection will affect 1971 and newer cars and trucks. Gasoline vapors vent into the air through leaky gas caps, even when the vehicle is not running. The fumes are toxic and contribute to ozone smog. Gas-cap gaskets can leak even though they look and feel intact.
Inspectors remove each vehicle's gas cap and place it on a testing device.
If the cap fails the test, the inspection will end, there will be no charge, and the motorist will be directed to replace the leaky cap. When the vehicle returns, the full inspection will take place after the new cap passes a retest. It is not required elsewhere in Washington. Emission Check stations are operated by Envirotest Systems, Inc., under a competitively bid contract with the state.