Last Update: Apr 12th, 2023
Smog Box Las Vegas

All About the Nevada Emissions Smog Test

If you're new to Las Vegas, you'll see these little "Smog" huts all over the place; it's the biggest racket in town (other than the gambling, of course). There are many brands. The main picture here is Smog Shop; there's also Jiffy Smog, Smog busters; it's exhausting trying to keep track. (Exhausting: get it?)

Jiffy Smog

If your car is more than 4 years old, you're required to pass a smog test in order to register your car. Unlike most states that just give you a sticker (and you'll get a ticket if you don't get it inspected), Nevada won't let you register your car. It's the dumbest thing on wheels.

How Emissions Testing Works

For cars sold after 1996, you have a computer interface below your dash where a technician can plug in a device to access your vehicle's computer. It's called On-Board-Diagnosics, Or OBD2 (2 for version 2). Your car monitors your emissions systems while you drive around and when a test completes a test cycle successfully, one of the monitors will go "green".

Nevada Emissions Test Zurich ZR8

There are 8 monitors. This is monkey-level stuff: red or green. Green is good, Red is bad. Well not really bad, it just means "not green". The good news is that once these lights are green, they stay that way. If you plug this in and the lights are all green, you're guaranteed to pass, as long as your check engine light doesn't come on before or during your test.

The fallacy of the Emissions test is that these monitors only tell you that your system was working properly during the test; if your car is 5 years old and your check engine light has never come on; the testing was done 5 years ago The theory is that if there's something wrong with your car, the check engine light will come on.

All About the Check Engine Light

Back in the day, before every single thing in your car was monitored by computer, when your check engine light came in it meant big trouble; you'd be draining your bank account shortly. Nowadays, it could mean nothing. Every tiny event can cause a fault "code", and fault codes make the check engine light come on. In my case, it was bad gas; Sam's Club to be exact. A total nothing burger; but it threw a code and my check engine light came on.

So why is this such a problem for emissions? Well in order to "clear the code" to get the check engine light to turn off, you have to reset the emission monitor tests. So now you have to start all over. All the monitors go red, and you have to drive around (maybe for weeks) before they all go green again.

The Stupidity of Emissions Tests

The problem here is that your monitors not being green have nothing to do with how much pollution your car is spewing. It's not 1976, modern cars would probably never fail an old time emissions test where they hooked an actual exhaust monitor onto your tailpipe. It's a scam. And it's a major pain in the ass.

The second dumb thing about emissions testing is that if there really is something wrong with your emissions system (say your check engine light comes on every 100 miles or so), you can still pass your emissions test if you can get tested in between events. If you know what you're doing, you can clear the light and then drive around enough to pass the test before the light comes on again. Totally ridiculous.

In my case it took 3 1/2 tank fill-ups to clear my problem; and 10 days before my registration was due was the last time the light came on. I have a device to clear the code, but I don't really drive that much, so my monitors weren't setting. I had to take a long drive; wasting gas and spewing exhaust into the air; so that I could pass my test.

So imagine 1000s of cars every day driving around for no reason other than to get some dopey monitors to turn green.

You don't need EVAP test to be Green to pass

As you can see above, not all of my monitors were green when I got my test, and my car passed. The Evaporator test (EVAP) can take weeks to reset, and it really doesnt have much to do with pollution. Even California doesn't require EVAP to pass the test; half the state would fail.

BTW, the nut jobs who run California only require an emissions test every 2 years; we have to get one every year. Let's all give the big 🖕 to the politicians in Nevada who refuse to repeal this nonsense that made sense 30 years ago but makes ZERO sense today. Note that Great States like Florida don't require emissions tests at all.

Emissions Good

It took 2 more weeks before my EVAP test completed.

Get yourself an OBD2 Reader

As a parting word, a friend of mine told me that he disconnected his battery to reset the monitors on purpose and then drove around to pass emissions. This is just the result of bad info on how the monitors work. Like I pointed out, the monitors don't "need" to be reset. Once they're green, they stay green. If you know that only one of them is red; you can google around and find out the kind of driving you need to do to get the monitor to turn green.

If you don't have one, I urge you to get on OBD2 reader for your vehicle. In modern times, you can't be going to a dealer every time something is wrong with your car; and even if you do, knowing what's wrong will keep them from ripping you off by telling you that you need stuff you don't really need. It's easy to use (even a girl can do it!). You can get one on Amazon for under $30.

I inherited the Zurich (literally) and I also have a veepeak bluetooth dongle that works with apps on your phone.


While some of the apps are comprehensive; they're overkill for most people. Bluetooth can be a pain in the butt; sometimes my phone just refuses to connect. These wired devices just work every time; no batteries required. It will pay for itself the first time you have a problem.

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Joseph T
This post was super helpful for me. My battery died 4 days before my registration renewal was up. I changed it and needed to clear my ECU due to multiple syatem faults trying to start the car with a weak battery. Every readiness test passed except EVAP. I'd already driven over 80 miles in 3 days just trying to get that EVAP test to pass. I endes up taking it in for a smog test and sure enough, it passed even with that EVAP test not completed. The smog inspector said NV allows 1 test to be unset. Thanks for your info. Now I dont have to pay a late registration fee.
Nevada SMOG Testing
DMV Smog testing was added as a Nevada Registration Requirement on 1 January 2023.
The Black 2011 Jeep, 4 WD, failed the computer portion of the DMV Smog computer test three times over a four week period.
I was told there are no errors to fix and we should drive it for about 100 miles to see if the computer problem would clear. Note: If the DMV computer test fails, they don't even look at exhaust gases.
We drove it and took it to a Jeep specialty shop. They couldn't even test it and had no idea how to fix it.
There appeared to be no recourse. Sooooo, with the Registration
expiring this Friday, 7 Jul, we decided to sell.
Fortunately, CarMax offered more than we would have gotten on a trade in.
Bye to a great vehicle. I think the Smog test was designed to fail.
Obviously you didn't understand 1 word in this article.
Thanks for writing this. I was so stressed but now I understand it!

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