A smog check usually takes 15 to 30 minutes from the moment your car is pulled into the bay. If the engine is already warm and there is no line, plenty of tests wrap up in about 20. The test itself is short. What stretches a visit is the wait before it, a cold engine, or a car that needs a second try.
Here is what happens in those minutes, what can push a visit past 30, and how to keep yours short.
How Long Does a Smog Check Take From Start to Finish?
For most drivers the whole visit breaks down like this:
- Check-in, about 2 to 5 minutes. The technician confirms your vehicle details and registration information.
- The inspection and emissions test, about 10 to 20 minutes. The technician looks over the required parts of your vehicle and runs the emissions test.
- Results and paperwork, about 2 to 5 minutes. You get your result, and a passing result is sent electronically to the DMV.
Add those together and you land in the 15 to 30 minute range. Arrive when the shop is quiet and you can be back on the road in around 20. Arrive in the middle of a rush and the same test can take an hour door to door, because the clock starts when you join the line, not when the technician starts the test.
If you want more detail on the test itself, our guide to what happens during a smog check inspection walks through each step.
What Can Make a Smog Check Take Longer
The Type and Age of Your Vehicle
Newer gasoline vehicles are mostly tested by reading the car’s onboard computer, which is quick. Older vehicles can need a tailpipe emissions test, which takes more time. Diesel and hybrid vehicles also follow slightly different procedures, so they can run a little longer. If you drive a hybrid, our post on smog checks for hybrid vehicles explains what to expect, and diesel vehicle smog checks in California covers that side.
A Cold Engine
An engine that has just been started is not running at its cleanest. The catalytic converter needs time to heat up before it works properly, which is why a car that barely moved before the test is more likely to struggle or need extra time to settle.
Busy Times at the Station
Smog checks bunch up at the end of the month, right before holidays, and on Saturdays, because that is when registrations come due and people have time off. Weekday mornings and early afternoons are usually calmer.
A Check Engine Light or Unready Monitors
A check engine light that is on will fail the test, so you will spend the visit learning what needs to be fixed rather than getting a certificate. A related problem is a car whose computer has not finished its self-checks, which often happens after a battery disconnect or a recent repair that cleared the codes. The technician may not be able to complete the test at all until the car has been driven enough. Our post on passing a smog check with the check engine light on explains how that works.
A Failed First Attempt
The test takes about the same time whether it is your first try or a retest. What changes is everything around it. A failed result means repairs, and repairs take days, not minutes. If that happens, what to do if your vehicle fails a smog check lays out the next steps, and the most common causes of smog check failure can help you head it off.
STAR Station Requirements
Some vehicles have to be tested at a STAR-certified station. That affects where you go, not how long the test takes. If you are not sure which type of station your car needs, see what a STAR station smog check is. The Bureau of Automotive Repair also explains the program on bar.ca.gov.
How to Get Through a Smog Check Faster
Fix the check engine light first. If it is on, the car will not pass, and no amount of speed at the station changes that. Get the cause diagnosed and repaired before you book.
Drive for 10 to 15 minutes before you arrive. A warm engine and a hot catalytic converter give you the best chance of a clean first result. A short highway drive works better than a few quick stops around the block.
Avoid the rush. Go on a weekday morning or early afternoon, and try not to wait until the last week before your registration expires. The last-minute crowd is the main reason a 20 minute test turns into a long wait.
Bring what you need. Having your registration or DMV renewal notice on hand saves time at check-in. Our smog check documentation checklist covers everything to bring.
Do a quick pre-check at home. Loose gas caps, low oil and neglected maintenance are avoidable reasons for trouble. The pre-test checklist on why cars fail smog checks and our guide to preparing for your smog check in California take a few minutes to read and can save you a return trip.
At AB Smog Check no appointment is necessary, so you can drive in during business hours. If you are close to your deadline, earlier in the day is your best bet.
What Happens After the Test
If your car passes, the station sends the results to the DMV electronically and you receive your certificate. You can then complete your registration renewal through the California DMV. The certificate is valid for 90 days, so do not sit on it. We explain the full window in how long a smog check is good for in California.
You can also confirm a result posted to your vehicle’s record at any time. Our guide to checking your vehicle’s smog check history shows how, using only your VIN or license plate.
If your car fails, the technician gives you a report that lists the reasons. Take it with you when you arrange repairs, then come back for a retest. AB Smog Check offers a pass or free re-test guarantee, so a retest at our station does not add to the cost.
Frequently Asked Questions
How long does a smog check take if there is a line?
The test itself stays at about 15 to 30 minutes, but a line adds to your total time at the station. On a busy day, allow up to an hour. Weekday mornings are usually the quickest.
Do I have to wait at the station?
Most people do. The test is quick enough that it is usually easier to stay than to come back. Our waiting area is there for exactly that reason.
How long does a smog check take if my car fails?
The test takes the same time, but repairs can take days, and you will need to come back for a retest once they are done.
How long is a smog check certificate valid?
For 90 days from the test date. Complete your registration within that window, or you may have to test again.
How often do I need a smog check?
Most vehicles need one every two years at registration renewal, though some are exempt and some have different rules. See how often you need a smog check and which vehicles need smog checks in California for the details.
Get Your Smog Check at AB Smog Check in Monterey Park
We keep the process quick and clear. You will know what the test involves before it starts, and you will get a plain explanation of your result afterward. Our STAR-certified station handles both regular and STAR-required vehicles, so you do not need to hunt for a second shop.
AB Smog Check 501 E Garvey Ave, Monterey Park, CA 91755 Phone: 626-280-2678
Hours: Monday to Friday, 9:00 am to 5:00 pm Saturday, 9:00 am to 3:00 pm Sunday, closed
No appointment necessary. Pass or have a free re-test.
