Get Visible Smoke Test Failure Consumer Information Sheet 2020-2024

The Diesel Smog Check involves two parts: A visual inspection of the vehicle's emission control system. A functional performance test to ensure the vehicle's emission controls are working properly.

1:52 6:56 VisibleSmoke Test training video - YouTube YouTube Start of suggested clip End of suggested clip With an unobstructed view observe the tailpipe area for at least 10 seconds. If any smoke isMoreWith an unobstructed view observe the tailpipe area for at least 10 seconds. If any smoke is observed the vehicle shall fail the test in this example this vehicle actually failed the smoke. Test.

The Ignition Timing Test applies to 1976 to 1995 model-year vehicles equipped with adjustable timing. If the under-hood emissions control label, an emissions application guide, or other reliable manufacturer derived references indicates timing is not adjustable, then the Ignition Timing Test is not required.

After performing the Idle Test (Step 3), continue to leave the vehicle's engine running at idle and go to the vehicle engine compartment. Open the hood to the engine compartment and determine whether any smoke is coming from the crankcase (PCV) system. Observe the vehicle's crankcase system for 10 seconds.

To report a smoking vehicle, please submit a complaint form for smoking vehicles through the California Air Resources Board website or call 1-800-END-SMOG (1-800-363-7664).

Excessive smoke, either black or white will cause a smog check failure. If your vehicle is emitting visible smoke, you will need to have the fault diagnosed and repaired before it can pass the smog check. Vehicles with severe engine damage may be emitting smoke from the engine compartment.

The Ignition Timing Test applies to 1976 to 1995 model-year vehicles equipped with adjustable timing. If the under-hood emissions control label, an emissions application guide, or other reliable manufacturer derived references indicates timing is not adjustable, then the Ignition Timing Test is not required.

When is a Smog Check required? A Smog Check is required every other year (biennially) as part of the vehicle registration process. The Department of Motor Vehicles (DMV) registration renewal notice will indicate if a Smog Check is required.