Going into a SMOG check without preparation is one of the easiest ways to waste money on a failed test. This checklist covers everything you should do before your California SMOG appointment so you can walk in with confidence.
The complete SMOG check checklist
Work through each item before you schedule your appointment. Fixing problems ahead of time is always cheaper than failing and retesting.
- Check engine light off. If the MIL is illuminated, your vehicle will fail automatically. Get the code read and the problem fixed first. Learn more about check engine lights and SMOG tests.
- Gas cap seals tightly. Remove it and put it back on. Listen for a click. Replace it if it is cracked, missing the gasket, or does not seal.
- Oil is clean and full. Dirty or low oil increases emissions. Change it at least a week before your test if it is overdue.
- Air filter is clean. A clogged air filter restricts airflow and can cause the engine to run rich, increasing emissions. Replace it if it looks dirty.
- Readiness monitors are complete. If you recently cleared codes or disconnected the battery, drive 50 to 100 miles of mixed driving before testing. Use an OBD-II scanner to confirm monitor status.
- No visible exhaust smoke. Blue or black smoke indicates oil burning or a rich fuel mixture. Both can cause a failure.
- Engine idles smoothly. Rough idle, misfires, or stalling can point to spark plug, vacuum, or fuel system problems that affect emissions.
- Tires are properly inflated. Some SMOG tests use a dynamometer (roller test). Correct tire pressure ensures accurate results.
- Coolant is at the right level. An engine that overheats or runs too cold can produce higher emissions. Make sure the cooling system is working normally.
- Drive for 15 to 20 minutes before the test. A warm engine and catalytic converter perform better during the inspection. Take a highway drive on the way to your appointment.
Check your DMV notice
Before you book, look at your DMV renewal notice carefully. It will tell you whether a SMOG check is required and whether you must go to a STAR-certified station. If STAR is required, not every station can handle your inspection.
What about the visual inspection?
The technician will also look under the hood for missing, modified, or non-compliant emissions components. If you have removed the catalytic converter, modified the exhaust, or disconnected any emissions equipment, those issues will cause a failure during the visual inspection portion of the test.
What if something on the checklist is wrong?
Fix it before you go. Paying for a SMOG test when you know there is a problem is throwing money away. A test-and-repair station can help with both diagnosis and repairs if you are not sure what is wrong.
Drivers in the Concord area can use the local SMOG coupon at Super Station Concord for testing and any needed repairs.