5 Mechanic Tips To Save You Money on California Smog Tests (Illustrated Guide)

5 Mechanic Tips To Save You Money on California Smog Tests (Illustrated Guide)

These five tips are sure to make your smog trip less of a hassle. I wrote this article specifically for passing smog in California as of 2019. However, these same tips and tricks probably apply to many other states in the USA as well. Most people are unaware of these simple things they can do to help prevent themselves from getting stuck at a bad smog shop paying way too much for unnecessary repairs.

Passing California smog in 2019 can be a real pain in the butt and here are some simple tips to make it as painless and cheap.

The main tips to passing California smog are

  1. Find a pass or don’t pay smog shop.
  2. If your car is older than 2000, find a shop that will also do a pre-test “sniff” to make sure your car will likely pass
  3. Fix any check engine light on before going to the smog shop (no car will pass CA smog with any check engine MIL light on).
  4. Ask if the smog shop will check if “all smog monitors are set” before running the test and charging you.
  5. If all monitors are not set, look up the “drive cycle” for your year, make and model– do it twice or three times.
  6. If the car is pre-2001, drive the car HARD and get it HOT before actually doing the smog test. 
  7. If it fails, make sure to get the printout showing WHY it failed and bring it with you to a qualified mechanic.
  8. If it just barely fails due to high hydrocarbons driving it hard and getting it HOT before the test may get it to pass.
  9. Take a smog test diagnosis of why it failed with a grain of salt– get a second opinion! Most smog only places are not qualified to be making any diagnosis related to failing smog. 

Saving Money:

Always ask for a pass or don’t pay smog test. If you can’t find one near you, then find one that offers a free retest.

When calling around to get the best price to remember to ask how much the smog test is out the door with the certificate fee. A lot of shops will list a smog fee that DOES NOT include the certificate. Normal cert fees range from 8-12 dollars.

If your car is older than 2000, ask for a pre-test sniff. If you are worried that the car or truck may not pass smog due to having high emissions (maybe it is an old Toyota truck or carbureted vehicle) then find a shop that will do a “pre-test sniff.” Most old school smog shops will do this, and it is one of the most important things to find in a good smog shop.

What is a pre-test smog sniff?

In California due to new smog laws “…Californians getting Smog Checks today may notice that the traditional tailpipe test used for many years has been replaced by a quicker, computer-based test for gasoline-powered cars model-year 2000 and newer, and for most diesel vehicles that are model-year 1998 and newer.” Therefore, the pre-smog sniff test may not apply to your car year– but it is always worth asking. If your car is OBDI(OBD1) then definitely ask for a pre-smog sniff and make sure your smog shop can actually handle a car that old. Certain smog shops no longer have the equipment to test older vehicles.

The smog technician will basically use the tester to get a readout of what your car is putting out at idle and at certain RPMS. From those numbers, he will have a pretty clear idea of whether the car or truck will pass during the actual test. Once the actual smog test is started officially the technician will never see the numbers until the test is finished (to make sure the test is done blindly).

I recently asked a smog shop to do a pre-test sniff on a truck I was certain would likely not pass due to high emissions but the mechanic forgot. He ran the test without checking the emissions out the tailpipe first. The truck failed due to extremely high hydrocarbons. It would have never been run for the official test had he done a pre-test sniff as I had asked. This being an error on his end led to him not charging me for the smog test and apologizing. Now my truck is in the system as a gross polluter which could have been avoided had he done a pre-test sniff as I asked. Therefore, please for saving yourself some headache get a pre-test sniff if you are at all concerned with it not passing. 

If the numbers are on point then run the test. If they aren’t, say the hydrocarbons are way above the passable limit, the smog technician can cancel out the test before it saves your car as having “failed smog” and you can do the repairs as needed. Just make sure to go back to the same smog shop and give them your business– they deserve it for going the extra mile. Many shops will refuse to do a pre-test sniff so call and ask first. 

Checking Monitors on 2000+ Year:

This shop is basically saying we will check your monitors for free before running the test. Always find a smog shop that offers the same deal!

Always ask the smog technician to please check to see if all monitors are set before running the test. This is another good one to call and ask the shop before if they will do this. Some shops will not check the monitors without being paid to do the test– but, avoid those shops! Many shops will check the monitors for free, and will happily do it without charging you.

This can be one of the biggest headaches when getting smog tests done. OBDII cars after 1996 all have computer monitors which must be run by the onboard computer before smog. When you go in for smog the technician connects to the computer of your car and asks it if all the smog monitors are ready. Depending on what state you are in and the year of your car you may be able to take the smog test with some monitors not set yet. However, if it doesn’t have all the monitors set yet and the smog technician starts the official test the car or truck will fail smog in the DMV system due to not having all the monitors set.

This can be scary to the customer who knows failing smog is a huge headache. What is the fix? Oftentimes the fix is driving the car more. It needs freeway miles, stop and go, and certain drive parameters to set all the smog monitors. The best way to figure out what your car needs is to find out what monitor isn’t setting. Then search google for “blank monitor not setting year make and model of your car.” You will likely find hundreds of other people that have had this problem, and potentially you may find a very specific driving pattern you should do to set the monitors on your car.

An example of how to get your car to set the monitors may be driving the car at 50-65 mph at 1/3 throttle for 10 minutes and then idle it with the AC on for another 4 minutes. Then hold the RPMs at 3000 for 2 minutes. Whatever the instructions are for your particular car follow them two or three times, and then drive back to the smog shop and ask them to check your monitors.

If they absolutely refuse to set after 1000 miles of driving, it is time to take it to a qualified mechanic for diagnosis. IT could be many variables causing one of the monitors to not set, and it may take some hours of diagnosis.

Smog Shops Offering the Wrong Diagnoses:

I really don’t like talking bad about mechanics or technicians because they are so undervalued by society. We rely on them to keep our cars safe and literally put our lives in their hands every day. That is why it is really really important to find a high-quality shop that has top of the line technicians.

That being said, many smog shop technicians are not qualified to be making statements or diagnosing why your car is failing smog. Especially if they are a “test only” smog shop.

Therefore, always take their recommendations with a grain of salt and get a second opinion. I have heard smog shops recommend catalytic converters like candy as a cure-all for everything. Since a catalytic converter can be one of the MOST expensive parts on a car, it is something that should not be condemned without a proper diagnosis by a trained professional.

Don’t freak out if the smog technician starts rattling off potential things that could be wrong. He is probably right, it totally could be your catalytic converter is bad, but your car needs a diagnosis! For example, a car that isn’t setting all of its monitors for smog does not mean it needs a new catalytic converter. It simply means more diagnosis or driving needs to be done to set the monitors.

I Failed Smog Now What?:

So, maybe you are getting to this post a little late and you failed smog. The most important thing now is to find out why it failed smog and for what reasons. 

Ask the shop to give you the printout of why it failed smog and research those numbers. You can post a photo of your printout on a mechanic help page (facebook for example) and see if anyone has some good tips. The smog printouts in California tell you why it failed smog (high hydrocarbons, high CO, etc.) and those are all very valuable clues to an experienced mechanic as to where his diagnosis should go.

Also, if it failed smog simply due to the monitors not being set then you need to drive it until the monitors set. This can be a headache because it can take a car 1000 miles sometimes to set all the monitors. That is why I highly recommend asking the smog shop to make sure the car has no check engine lights stored and all the monitors are set before running any smog test.

There are also smog test programs that help you pay for repairs in California. There also exists a program where you can get $500 towards repairs and a smog waiver in California. You can also request seeing a smog referee if you meet certain circumstances. For all official information relating to smog in California click here.


The general old-school tips you can find anywhere online still apply to get your car to pass smog in California in 2019. Get it hot, drive it hard, use high-quality fuel, check the spark plugs and fuel filter etc. These are all great and I highly recommend watching some YouTube videos about getting a car to pass smog/reading about it. But those tips have been around forever, and these are some more modern tips to making sure you don’t waste your money getting your car to pass smog.

The real pro tip is finding that smog shop that has highly experienced technicians and offers a pass or don’t pay type program. Make sure your car is likely to pass by getting a pre-test sniff done and having them check that all smog monitors are set and no check engine DTC is stored in the cars computer. If everyone did this before smogging their cars some smog shops would go out of business and others would flourish.

I hope you enjoyed this illustrated smog passing tip blog post. There are some products that for certain situations may help your car pass smog, and some of them even offer a guaranteed to pass result. I have actually used one of these in a car and passed the smog test after failing for high hydrocarbons, but I had also done some maintenance to the car.

Some of the products you may want to check out to help you pass smog or to check your own smog monitors/check engine codes:

Guaranteed to Pass Engine Cleaner (I have had success with the CRC version– but, as you can see mixed reviews)

Buy an OBDII code reader with smog readiness capability (make sure it can tell you what smog monitors are set)

You can also try Lucas Fuel Cleaner and add it to your car before Smog (drive the car hard and get it hot)

If you live in a cold climate or it is winter time, think about installing a winter radiator cover to help your car get up to operating temperature and stay there (cars that are running cold will sometimes fail smog or not set readiness monitors). You can also use some cardboard and tape like this guy on YouTube shows you how to do. Just make sure not to overheat your car!

You can use a scan tool that has live data capabilities to check ECT (Engine Coolant Temperatures).


Leave a Comment

Your email address will not be published. Required fields are marked *