How to Pass the DMV (Car / Auto) Smog Test / Check. The Ultimate Smog Test & Emissions Guide. Will Your Vehicle Pass?

This article is in reference to older cars and limited budgets. The info is generally organized in ascending order of costs involved. There are also lots of maintenance tips.

An alternate title might have been, "The Top Ten Ways to Pass the Smog Test". But there are way more than 10 ways here. And, frankly, no one way would probably do it. The procedures and items listed below are mutually interactive. It is best to do as many as possible. "The Top Ten Ways to not flunk the Smog Test" could also be a good title; since failure to implement many of the items here would probably cause grief.

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Smog test time is as good a time as any to do right by your car. By the time you’re done, you’ll feel like you’ve got a new car again.

This article is especially applicable to "smog test only" and "ca smog test" situations.

If your car takes regular gasoline, fill the tank with premium prior to the smog test.

Premium gas will do:

1. Absolutely nothing for your mileage.

2. Absolutely nothing for engine maintenance or vehicle life expectancy.

It will, however, burn a little cleaner (a.k.a. reduced smog emissions); and that is the objective here.

Does your state mandate 10% ethanol during certain times of the year? If possible, postpone or accelerate your test time so as to take advantage of this. You want your tank full of 10%-ethanol- gas when you take the smog test.

Like premium; ethanol does nothing for your car, but does burn cleaner (a.k.a. reduced smog emissions).

Do not get the bright idea of adding your own extra ethanol (or whatever). It is illegal to do that; and you will get caught.

The higher the humidity, the better (and cleaner) your engine runs. If possible, do the smog test on a rainy day.

Temperature is also a consideration. Your vehicle will do better on the smog test when the outside temperature is 60 degrees, as opposed to when it is 90 degrees.

Doing the smog test first thing in the morning is usually your best bet. Besides, people are generally in a better mood then (more about that later).

Conversely, do make sure your engine is fully warmed up before arriving at the test station.

Most people use their car only for short trips most of the time. This does not provide sufficient time for the battery to fully recharge after starting.

When the battery is not fully charged, a weak ignition spark can occur. A weak ignition spark will result in poorer mileage and much higher smog pollutants.

Be sure your battery is fully charged before the test.

Many people will trickle-charge their battery overnight every once in a while. This can add years to the life of a battery. Beware overcharging.

Chilton publishes manuals for every year, make, and model of car; including yours. It is written for the consumer; you don’t have to be a mechanic with ten years experience to benefit from it.

The manual will tell you:

1. About all routine maintenance that needs to be done; and when and how to do it.

2. Where all the car components are (example: where is the PCV?).

3. How to do many common repairs; and especially how to avoid the many pitfalls/traps that were designed into the vehicle and are just waiting for you…

This manual will give you the information you need to do everything described in this article; and a whole lot more. The instruction level starts at rank beginner and proceeds to as advanced as you care to go.

This manual will save you many hours of grief and a lot of money.

If you plan to keep your car for any length of time, then this book is a very good minor investment. You don’t have to be a rocket surgeon to understand it. In fact, you can thumb through it while watching TV.

A note for our women readers: Chilton’s Manuals aren’t just for men. Don’t go thinking that the information in this article or in the manual is beyond your comprehension just because you happen to be a girl… In fact, as a woman, you should be especially interested. Read the book. Then the next time some unethical mechanic stereotypes you and tries to rip you off, you will be prepared. And just so you know: men get scammed at least as often as women, probably even more so. It’s all just a matter of knowing the concepts and terminology; those without the knowledge are the ones most often targeted.

Don’t forget to avail yourself of the comments section if so inclined.

Is your car due for an oil and filter change? Well, now is the time.

This is one of the few maintenance items that it is best to give to a shop to do. You won’t save money doing it yourself; and you will save yourself a lot of mess and aggravation. The going rate is around $30.

While changing the oil and filter, they’ll do a lot of the other maintenance stuff for you as well. How are the radiator coolant, transmission fluid, power steering fluid, and brake fluid doing? How about the differential, battery water, and tire pressure?

Important note: Many shyster places will try and tell you they have discovered that your car needs several hundred dollars worth of additional work. This is particularly applicable to certain national chains.

Do an advanced Google search on the place you intend to visit. The search query should be: “entity-name”; with any/all of the words: “scam”, “ripoff”, “rip-off”. If there are several pages of complaints, then obviously select someplace else.

Ask people you trust for recommendations.

Does your car need a new air filter? Now is the time. Wipe away all the dust in the canister when you replace it.

A clogged/disconnected/broken PCV causes a lot of flunked smog tests. It is an inexpensive and easy part to clean/fix/replace. Make sure yours is ok.

A fouled spark plug causes a lot of flunked smog tests. If your vehicle is mostly used for short trips, fouled spark plugs can result. Doing a two-hour roundtrip at normal freeway speeds for some useful endeavor before the test might clean out the carbon and other junk in the engine and plugs.

Do your spark plugs need to be replaced? A mechanic will charge ~$100 to do that for you, plus the inflated cost of the plugs. Or you can earn yourself a $100 (tax free) and do it yourself.

There are a lot of mistakes you can make when changing plugs. It is imperative that you read the Chilton’s manual first; then decide. Some auto parts stores have tool-loaner programs.

Depending on how the plugs are positioned, changing them can be a lot of work and frustration. You don’t have to do all of them at once. Do just one or two a day if you want.

Does your car have a mechanical distributor and rotor? Is it original equipment? Does the car have over 80,000 miles? If you replace the distributer cap and rotor, the improvement in performance will amaze you.

The distributer cap and rotor are easy and inexpensive parts to replace. However, you need to read the manual first; otherwise you’ll mess it up.

If not replacing the distributer cap, be sure and check it for cracks and other defects. Cracks in the distributer cap can cause the engine to fail the smog test.

Are the spark plug wires original equipment and over 80,000 miles old? If so, there may be cross-sparking. That’s not good for the engine or the smog test.

If so inclined, observe the engine running in near-total darkness (flashlight anyone?). Look for sparks between the wires or from the wires to metal. Don’t give yourself carbon monoxide poisoning while attempting this. Don’t touch anything. Avoid all moving parts. Leaning over the engine while wearing a tie would be especially unwise.

Better to just go ahead and replace the wires… Mistakes can be made while doing this, so read the Chilton’s Manual first. And do just one wire at a time; don’t even think about trying the mass disconnect/removal/replace scenario.

Does your car have a carburetor? Spraying Gumout in it and on it will do wonders; both as to performance and reducing smog pollutants. Follow the directions on the spray can. Do not overuse. Do not overspray. Do not do just before the smog test.

Does your check-engine light remain dark when starting the car? If so, you probably have a burned out bulb and you have automatically flunked the smog test.

Does your check-engine light remain on after the engine has started? The warning light could indicate something minor or something serious. Either way, you have automatically flunked the smog test.

Depending on your make/model/year of car and the nature of the problem; the Chilton’s Manual might be able to solve this for you without having to go to a mechanic.

Disconnecting your car battery for a minute could reset your check-engine light back to norm. However, you would lose the stored error codes. Those error codes are what would tell you is wrong.

Your car probably has more computer technology in it than the 1969 Moon Lander. One poorly connected wire can cause a smog test failure.

Do a visual inspection. Make sure there are no loose wires. Make sure all wires are firmly connected. If you find anything even remotely suspect, disconnect and reconnect the wire a few times to remove oxidation; maybe sand it a little with emery paper as needed. If any of the plastic connector/clamp parts are broken; they’ve got to be fixed.

Finding/fixing a connection could solve a check-engine light problem (may need reset).

Vacuum leaks can cause smog test failures.

Check all those little hoses around the carburetor, air cleaner, PCV, here, there, and everywhere. Make sure all are firmly connected. Make sure none of them have any splits, tears, etc. Replace anything suspect.

Risky business… If you spray a water mist near/around the sides of your carburetor while the engine is running, and the engine speeds up; you have a vacuum leak. The risky business part relates as to what to do about it. Can you pinpoint the exact location of the leak? Examine the gaskets; look for splits/cracks/stains. If you can determine the exact location of the vacuum leak, you have a decision to make: try to do a kluge fix; give a mechanic some serious money; or do nothing, roll the dice and take the test. This article will not address as to what that decision should be.

A fixed vacuum leak may solve a check-engine light problem (may need reset).

If the timing is not within specifications, then you will flunk the smog test. People have also been known to advance the timing above specs to increase performance. An out-of-spec engine idle speed will also cause a test failure.

If your vehicle is of the points/dwell generation, you will need to do that before doing the timing and idle.

The Chilton manual will tell you everything you need to know to check and readjust the timing and idle. The factory specs for the engine timing, idle speed, and other info is stamped on a metal plate or decal located towards the front in the engine compartment. One of your local auto parts places may have a tool loaner program for the timing light and special wrench you may need.

Or you can skip this section and just go ahead and take the smog test. In fact, now would be a good time to mention that the “skip it” option applies to all sections of this article. Only you can decide which items to implement and which to forgo.

Does the vehicle’s exhaust system have any holes in it? If so, you have automatically flunked the smog test.

Does the gas cap not seal properly? If so, you have automatically flunked the smog test.

Does your state include a safety test along with the smog test? If not yet, someday they will.

Make sure all your lights work: brakes, turn signals, etc.

Good a time as any to check the tires for uneven wear, sidewall splits, tread depth, embedded nails, etc.

Wash/clean your car inside and out. This includes removing all biohazards and other trash. Check under the seats. Clean the windows inside as well as out. Wipe/brush the inside dust off everything. A pan of baking soda will remove odors (in a few days).

Upholstery patch-up kits don’t cost that much.

Does the body have scratches? Auto stores sell colored “crayons” that will permanently make it look ten times better.

Come to think of it, when is the last time the poor thing has been waxed?

Wipe the dust off all the top surfaces in the engine compartment as well.

You want your car to look as good as possible. Presenting the technician with a car that looks like it’s been treated as a POS is never a good idea. The POS might translate to a WTF; and your car is smog test history.

You usually don’t have to worry about the test technician. As an employee, his/her only agenda is to do a quick, fair test and move on to the next one.

You’ve done your part by presenting the technician with a clean, apparently well-maintained car; thus doing nothing that would deter/distract the technician from his/her original goal.

It’s the person at the front counter that you have to worry about. If that person instructs the technician to flunk your vehicle; then it’s probably going to happen.

There are at least three personality types that you need to be aware of:

1. First, of course, is the thief. Depending on how your state sets things up, you may be scammed into paying for unnecessary repairs.

2. Second, is the Self-Appointed-World-Policeman. Some of the things that can "set-off” the self-appointed-world-policeman are: any/all facets of your appearance, the perception that you are not a contributing member to society, the perception that you are “low-class”, the perception that you are “high-class”, the perception that you are somehow deviant in some way, shape, or form from what is considered a normal human being.

3. Third, is the overly-sensitive, self-defensive personality-type. This personality type usually develops from being hammered in high school for something or the other; usually some sort of physical appearance attribute, though it could be for other reasons as well. Practically anything can set this personality-type off: what you say; what you don’t say; voice intonation; eye-contact, non-eye-contact; use of any word that could be even remotely construed as a double-entendre.

These personality types are more prevalent in some counties/cities than in others. The second and third personality-types may possibly be more prevalent in the smaller shops.

To help reduce your odds of triggering these personality types into “selecting” you, you can do the following:

1. Don’t wear anything with writing on it.

2. Don’t wear anything with pictures on it.

3. Don’t dress rich. Don’t dress poor. Don’t dress sexy.

4. Don’t wear any political, religious, or pornographic artifacts.

5. If you have tattoos, cover them up if possible.

6. If you smoke: do not smoke in the car on the way to the test; do not smoke while waiting for the test.

(Of course all of the above is a direct violation of your civil rights. Of course it is completely unfair. However, what do you want to do? Pass the smog test or attempt to “cure” a warped/distorted personality type? It’s up to you.)

Here are some other things you can do:

1. Do not be adversarial.

2. Do not volunteer any unnecessary/irrelevant information.

3. Do not engage in any unnecessary/irrelevant conversation whatsoever.

4. Be open and honest, yet keep the interaction to a minimum.

5. Do not show fear. Do not suck up (sucking up is a sign of fear).

Smog shops that advertise on the internet are probably your best bet. They know that you know how to go to the various forums and trash them if they try anything unethical. They know that you know how to find all the relevant federal, state, county, city, and consumer related addresses if you wish to send complainant emails.

Besides, they are in a very competitive business; some of them are most likely handing out big, fat coupons or discounts.

Whoever you select; do the same scam search that you did for the oil-change shop.

And check the state website to be sure they are really licensed to do smog tests.

First, it’s not the end of the world; just a pain in the …

Your state may have an Auto-Repair-Program that will provide financial assistance. Your state may have a Special-Dispensation program to give you time.

The Smog Test Station should have this information. It would also behoove you to troll your state’s DMV website and the secondary/separate smog test website (if they have one). The website(s) might also have a complaint section. The website address(es) should be printed on your Vehicle Registration Renewal Notice.

One way or the other you will get through it; and you will have a nice, “new” car again in the process.

This can be a dangerous game. It all depends on which city and/or county you happen to live in.

The Scenario:

You put off the test until the last minute; and you flunk it. There is no way the state will complete your financial assistance application in time for you you to get the repairs done before your tags expire.

First, if the state will let you, pay the registration fee before the deadline anyway. You really don't want to be subjected to the no-doubt excessive late payment penalty fees; this is premised on the belief that you will eventually enable your vehicle to pass the test.

To drive or not to drive; only you can decide. In some places you will only be cited; in other places your vehicle will be impounded. Getting your vehicle out of the impound lot will be a real challenge indeed. Even if you are able to pay the ransom and are allowed to retrieve it, you might be required to pay to have the thing towed on a flatbed truck; presumably to the smog repair shop.

Just being cited may not be that much fun either. In many cities and counties, “justice” has been tossed out the window when it comes to traffic tickets. The fine may “only” be $50 to $100, but they are not done yet. Depending on where you live, there may be an additional $200 to $300 tacked on as “fees”. Since they are calling it a “fee”, instead of a fine, they can and do pretty much make up whatever they want.

Bottom line is to do what you need to do for the car and get the test done as soon as possible. By all means use the aforementioned seasonal rainy weather and ethanol stratagems when feasible. But if you intend to utilize the state's financial aid program, be sure to give yourself sufficient time.

You are not alone. Please share the above information so as to help others. The more people that are knowledgeable, the better off we all are.