First, you need to figure out what is causing the check engine light to be turned on. To do so, you will need a device called an On Board Diagnostics (ODB-II) code reader and plug it into your car. The device will display the error code(s). Since ODB-II code readers can can anywhere between $100 to $300, you should go to your nearest auto parts store such as O’Reily’s (Kragen), Autozone, or Pep Boys because they will let you borrow a code reader as long as you leave some collateral such as an ID at the front desk.

Connect the ODB-II reader to your car’s serial port interface usually located under the dashboard on the driver’s side of the car. Press the “Link” button on the reader and it will display a listing of error codes. Write these error codes down. You can ask the friendly person at the auto parts store about the error codes and even the parts that need to be replaced. You should also research about the error codes online at odb-codes.com.

Many check engine light problems stem from a faulty oxygen sensor in the exhaust system. Error code P0136, for example, indicates that the oxygen sensor at Bank 1 Sensor 2 is faulty. Bank 1 refers to the side of the engine that has the #1 cylinder which is typically but not always the passenger side. Sensor 2 indicates the second sensor from the front of the car.

If you’re handy, DIYer, and able to replace the parts yourself, you can potential save yourself at least $200 in parts and labor at the repair shop. If can’t do it yourself, at least, you can go to the repair knowing what’s wrong with your car and save yourself from any run around.

Once you have replaced the broken parts, you can drive your car for approximately 60 miles and it will automatically clear the error codes. The check engine light will turn off. If repaired at a shop, the shop can clear the error codes with ODB-II code reader.

With the check engine light off, your car is ready for the smog check.

Note: Even though you can turn the check engine light off temporary with the code reader, that doesn’t solve the problem with your car’s emissions and you will most likely fail the smog check. Save yourself some time and money by fixing the problem first.

New Features and Improvements

Appointment Notification

The DMV’s Telephone Appointment Notification system gives you a call about your upcoming appointment. It’ll tell you the date, time, location, and purpose of your appointment three days prior. If you don’t answer, it’ll even leave a message.

Virtual Hold

You will be giving the option to be called back by a customer service agent. If you’re expected wait time is longer than five minutes, you will be given the option. Simply leave a callback number.

Self Service Terminals

Get your car renewal and registration tags and card at the Self Service Terminals. The terminals accepts cash, credit card, or check. Every step is automated for speed and convenience. There are currently 25 in south California DMVs and Sacramento’s La Mancha branch.

Mobile Apps

The DMV now offers “DMV NOW” mobile apps for both iPhone and Android. The app lets you find all DMV office locations and their actual wait times. It gives turn by turn driving directions to your nearest DMV local office. It also has practice written tests along with access to a library of driver education videos. Download here:

• iPhone – DMV NOW
• Android – DMV NOW

Schedule an Appointment

As before, you can still schedule an appointment for an office visit or the behind the wheel driving test on the new site. The user experience of making an appointment is so good you might actually make an appointment instead of taking a chance at the long lines at the local office.

English and Spanish

The site is available in two languages: English and Spanish.

Check out the new site: California DMV

DMV Registration Renewal

The DMV registration renewal notice will indicate if a smog check is required for your vehicle. Depending on which county your vehicle is registered, you may be required to pass a smog check before obtaining your new registration and new year sticker. Additionally, vehicles six years or less do not need a smog check. Instead, owners of vehicles 6 years or less will pay a smog abatement fee of $20 (as of 2011).

Buying a Car

When you purchase a vehicle, the seller must provide the buyer with a valid smog check certification. In other words, the seller is responsible for performing and passing a smog check before the sale or transfer. The smog check certification is valid for 90 days. If the vehicle has passed a smog check in the past 90 days, the seller or buyer is not required to perform another smog test. Be sure to obtain a copy of the smog check certification from the seller as a precaution.

If the vehicle is four years or less (current year minus three years), a smog check is not required by the DMV to sell or transfer the car.

Selling a Car

When you sell a vehicle, the seller is responsible for passing the smog check before the sale. The smog check certification is good for 90 days. Sell the vehicle within 90 days of the smog check and you do not need another smog check. Again, vehicles that are four years old or less do not need a smog check.

Vehicle From Family Member

Smog check is not required if you get a car from a spouse, domestic partner, sibling, child, parent, grandparent, or grandchild. Any other family member requires a smog check.

Test only smog check stations are licensed by the state to perform only tests on vehicles. They are prohibited from performing any repair services. Gross Polluters can be certified at these stations. Potentially high-polluting vehicles also known as gross polluters in the state’s smoggiest regions are directed to these stations for their initial Smog Check inspection, as specified on the Department of Motor Vehicles registration renewal form. In addition to gross polluters, regular vehicles are randomly chosen to have their smog check at test only stations. An oil change is not considered a repair service so many test only smog check stations will offer oil changes as an extra service.

Test and Repair Smog Check Station

Test and repair stations are licensed by the state to provide smog check tests and repairs to most vehicles. Under current law, test and repair stations are prohibited from certifying repaired gross polluters or vehicles that have been directed to test only stations for inspection. Vehicles that are not gross polluters or selected to perform a test only smog check can be brought to a test and repair station to complete their smog check. The test and repair station can both test and perform maintenance and repairs to your vehicle in order for it to pass the smog check. However, only test only stations and Gold Shield stations are able to certify repaired gross polluters.

Gold Shield Stations

Gold Shield stations are licensed test and repair stations that have received additional certification by Bureau of Automotive Repair (BAR). In addition to the services provided by regular test and repair stations, Gold Shield stations can certify vehicles identified as gross polluters. They can also perform the “after repairs” certification of vehicles directed to test only stations for an initial inspection, as long as the Gold Shield station has performed repairs to the directed vehicle. Gold Shield stations also contract with the Bureau of Automotive Repair to perform state subsidized emissions related repairs on vehicles participating in the Consumer Assistance Program. Gold Shield stations located in the Basic program areas of the state can certify Enhanced area vehicles for new and used car dealers who purchase them and offer them for sale in the Basic and Change of Ownership program areas.

Repair Assistance Requirements

• The vehicle must have failed a “biennial” (every other year) Smog Check inspection (aborted, manual mode, and training mode tests do not qualify).
• You must be the registered owner and not have previously repaired this vehicle through CAP, as of July 1, 2009.
• You must pay all appropriate vehicle registration fees to the Department of Motor Vehicles.
• The vehicle must not have a tampered emissions control system.
• The vehicle must not be undergoing a transfer of ownership or an initial registration in California.
• The vehicle must not be registered to a business, fleet, or non-profit organization.

Income Requirements

You must also meet the Income Eligibility Requirements.

Vehicle Requirements

Vehicle Equipment Requirements

• All doors
• Hood lid
• Dashboard
• Windshield
• At least one side window glass
• Driver’s seat
• At least one bumper
• Exhaust system
• All side and/or quarter panels
• At least one headlight, one taillight, and one brake light

Vehicle Operational Requirements

• Vehicle must be driven to a CAP contracted dismantler under its own power
• Vehicle engine starts readily through ordinary means without the use of starting fluids or external booster batteries
• Vehicle drivability is not affected by any body, steering, or suspension damage
• Vehicle is able to drive forward a minimum of 10 yards under its own power
• Interior pedals are operational

Retirement Eligibility Requirements

• You must be the registered owner with vehicle title issued in your name, and not have retired a vehicle (a joint owner must not have retired two vehicles) through the Consumer Assistance Program (CAP) within the last 12 months.
• The vehicle shall have a gross vehicle weight rating of no more than 10,000 pounds including a passenger vehicle, truck, sports utility vehicle (SUV) or van.
• The vehicle must pass a visual and operational inspection. (See above)
• All vehicles undergoing an initial registration in California are ineligible.
• All vehicles registered to a business, fleet or non-profit organizations are ineligible.

AND

Vehicle FAILED smog check

• The vehicle must have failed its most recent Smog Check inspection (aborted, manual mode, and training modetests do not qualify).
• You must pay all appropriate fees for the vehicle with the Department of Motor Vehicles (DMV).
• The Smog Check failure must not be due solely to an ignition timing adjustment, or a failed gas cap functional test.
• The vehicle must have been continuously registered as an operable vehicle in California for the 24 months prior to the postmark date of the application;or
  • The vehicle was placed in non-operational status for a total of 60 or fewer days for the 24 months prior to the postmark date of the application;or
  • The vehicle registration has lapsed for less than 121 days for the 24 months prior to the postmark date of the application.

OR

Vehicle PASSED smog check

• The vehicle must be continuously registered as an operable vehicle in California for at least 24 months prior to the postmarked date of the application;or
  • The vehicle was placed in non-operational status for a total of 60 or fewer days during the continuous 24 month registration period and occurring at least 90 days prior to the postmarked date of application;or
  • The vehicle registration has lapsed for less than 121 days during the previous 24 month registration period,provided that the vehicle is registered for at least 90 days prior to the postmark date of the application.
• The vehicle may be eligible if primarily driven in California for the last two years (not have been registered in any other state or country in the last two years). Documentation of operation in California includes the following:
  • Proof of insurance for the last two years;or
  • Invoice(s) (showing the vehicle identification number) for vehicle repairs and/or maintenance during theprevious two years and proof of owner’s residence in the State during the same period.

Dismantler List

Consumer Assistance Program Dismantlers list can be found here

The Bureau of Automotive Repair (BAR) manages and administers the Consumer Assistance Program (CAP). CAP allows California consumers to retire a qualified vehicle and receive $1000 or $1500 if they meet low income eligibility requirements. Additionally, the Consumer Assistance Program gives up to $500 of financial assistance towards emission related repairs for vehicles that failed their smog check.

How can I retire my vehicle?

You can retire you vehicle at any time and for any reason. However, you and your vehicle must meet the vehicle retirement requirements in order to receive $1000 or $1500 if you meet low income requirements.

How can I get financial assistance to repair my vehicle?

If your vehicle fails the smog check and you meet income requirements along with the repair assistance requirements, you can receive up to $500 towards emission related repairs. A co-payment of $20 is required and goes towards diagnosis and repairs.

How i can apply for CAP?

You must first complete and submit an application for CAP before retiring or performing any repairs if you want any financial assistance. Consumer Assistance Program Application.

How long does approval take?

Once the application is submitted, applications are processed within 7 to 10 business days. Same day application processing is available at any of the BAR’s 12 office locations. Once approved, you will receive a Letter of Eligibility along with further instructions.

Where can I repair my vehicle through CAP?

You must repair your vehicle at Gold Shield stations under contract and licensed with the BAR. Do not perform any repairs without prior approval through CAP. To find a Gold Shield station near you, use the search feature of the site and filter by Gold Shield.

Where can I retire my vehicle?

You must retire your vehicle at a dismantler licensed and under contract with the BAR. If seeking financial assistance, do not dismantle your vehicle without prior approval and receiving your Letter of Eligibility. List of dismantlers

For more details on the Consumer Assistance Program, download and read the application.

%O2: Oxygen is a colorless, odorless gas necessary for life on the planet and also for engine combustion to occur. The atmosphere is comprised of approximately 21% oxygen. High levels of O2 emissions can indicate a problem with the catalytic converter. High or low levels of O2 emissions are not grounds for a vehicle failing the Smog Check; the measurement is meant as a diagnostic tool for technicians. O2 is measured in percent.

Air Injection: Also known as the smog pump. Pumps air into the exhaust manifold to burn unburned fuels (hydrocarbons).

AVE: The average emissions for vehicles in the same Emissions Standards Category (ESC). ESCs are based on model year and whether the vehicle is a passenger car or a light-, medium-, or heavy-duty truck. The average emissions reading is meant as a guidepost for technicians when repairing vehicles that fail a Smog Check; it has no effect on the pass/fail result of the emissions test.

Acceleration Simulation Mode (ASM): This is the test type for vehicles operated on a dynamometer (treadmill like device) which simulates actual driving conditions.

Bureau of Automotive Repair (BAR): Part of the California Department of Consumer Affairs, the Bureau of Automotive Repair (BAR) is a consumer protection agency focused exclusively on automotive repair issues. BAR licenses auto repair dealers, Smog Check stations, and Smog Check technicians. BAR administers the Smog Check program, as required by law. BAR investigates complaints from consumers about auto repair establishments, and recovers millions of dollars for consumers each year. BAR is completely separate from the Department of Motor Vehicles and the Air Resources Board.

Catalytic Converter: Located between the exhaust manifold and the muffler, this device uses precious metals as a catalyst to turn hydrocarbons, carbon monoxide, oxygen, and oxides of nitrogen into carbon dioxide and water vapor.

Certification: Indicates whether your vehicle was manufactured to meet United States Environmental Protection Agency or more stringent California emissions standards.

Carbon Monoxide (CO%): Carbon Monoxide is a colorless, odorless gas that is fatal to many life forms in moderate concentrations. CO emissions are often the byproduct of an overly rich fuel mixture. Unhealthy levels of CO emissions result in a vehicle failing its Smog Check. CO is measured in percent.

Consumer Assistance Program (CAP): The Consumer Assistance Program is available at participating Gold Shield stations for motorists who need financial assistance (up to $500) making repairs to their vehicle when it fails a biennial (every other year) Smog Check.

Cylinders: The number of combustion cylinders in the engine (usually 4, 6, or 8).

Directed Vehicle: In order to comply with state law, the California Department of Consumer Affairs/Bureau of Automotive Repair (DCA/BAR) directs a portion of the vehicles registered in Enhanced Smog Check Areas to Test-Only and Gold Shield stations. These vehicles are called Directed Vehicles. Enhanced Areas are those parts of the state with “serious,” “severe,” or “extreme” ozone pollution problems.

DMV ID Number: A number used to locate the electronic smog certificate in the event it is electronically misfiled.

EGR Functional: During the Smog Check inspection, the technician performs a functional test of the EGR system per the vehicle manufacturer’s instructions. This ensures the EGR system is operating as designed.

EGR Visual: As part of the Smog Check inspection, the technician performs a visual inspection of all emission components the vehicle is equipped with, including the EGR system. The technician visually inspects the EGR valve and associated plumbing for defects or modifications. The technician will either pass or fail the fuel cap visual test based on observations made during the test.
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Emissions Control System (ECS): The Emissions Control System is any of a number of separate emissions control components which, together, reduce the level of pollutants emitted from a vehicle.

Exhaust Gas Recirculation (EGR) System: The vehicle’s Exhaust Gas Recirculation system reroutes exhaust gases back through the intake manifold to lower engine temperatures and, in so doing, reduces NOx emissions. The EGR functional test is part of the two-speed idle (TSI) test, but is not necessary for the ASM (BAR-97) test because that equipment tests for NOx.

Emissions Inspection System (EIS): The EIS can be defined as the complete BAR97 system, the analyzer, dynamometer and peripheral devices.

Emission Standards Category (ESC): ESCs are the pass/ fail emission level cut points for a specific class of vehicles. For example, 1975 through 1978 trucks with a Gross Vehicle Weight Rating (GVWR) over 8500 pounds would have the same cut points, therefore, they are in the same ESC.

Emissions Test: The third of the three vital parts of the California Smog Check. This is where the emissions analyzer tests actual emissions from your vehicle, as measured at the tailpipe. Only the emissions test can label a car a Gross Polluter. Emissions measured include Carbon Monoxide (CO), Carbon Dioxide (CO2), Hydrocarbons (HC) and Oxygen (O2). In California’s most polluted urban areas (Enhanced Areas), the emissions test also measures levels of oxides of nitrogen (NOx).

Engine Size: Measured in displacement of either cubic inches, cubic centimeters, or cubic liters.

Evaporative Emission Control System (EVAP): The EVAP system prevents raw gasoline from escaping the vehicle and evaporating into the atmosphere. As part of the inspection, the technician visually inspects the EVAP system and associated plumbing for defects or modifications. The technician will either pass or fail the EVAP system based observations made during the test.

Exhaust: Usually either single (one pipe) or dual (two pipes).

Exhaust Gas Recirculation (EGR): The vehicle’s Exhaust Gas Recirculation system reroutes exhaust gases back through the intake manifold to lower engine temperatures and, in so doing, reduces NOx emissions. The EGR functional test is part of the two-speed idle (TSI) test, but is not necessary for the ASM (BAR-97) test, because that equipment tests for NOx.

Fail: The level of harmful emissions from this vehicle, on this portion of the test, exceeds the range of what is reasonable for this model/engine combination, and is contributing to unhealthy air in California.

Fillpipe Restrictor: A functional test of the fuel pipe restrictor is performed only on vehicles being initially registered in California. If the fuel pipe restrictor is oversized due to tampering, then the fuel pipe restrictor functional test fails.

Fuel EVAP Functional: A functional test of the evaporative emission control system is under development by the Bureau. Until the test is implemented, the technician will enter “non applicable” into the analyzer for this test.

Fuel Cap Integrity Test: Tests whether gasoline fumes can leak out from your tank around the cap. Gasoline fumes contain high levels of harmful pollutants, including benzene, a known carcinogen. Studies by the United States Environmental Protection Agency show that around 30 percent of all the emissions from a vehicle are in the form of fuel evaporation, usually from the fuel tank.

Fuel Cap Visual Test: As part of a Smog Check inspection, the technician visually inspects the fuel tank cap for defects, (i.e. cracked or deteriorated rubber seal). The technician will either pass or fail the fuel cap visual test based on observations made during the test.

Fuel Evaporative Controls: Also known as the charcoal canister, this system stops vapors from the carburetor bowl and the gas tank from evaporating into the atmosphere.

Fuel Type: Only vehicles fueled by gasoline, natural gas, and propane are currently included in the Smog Check program. Light-duty diesel vehicles are excluded.

Functional Inspection: The second of the three vital parts of the California Smog Check. The functional check ensures the correct vehicle timing and EGR System function. The engine malfunction light is also part of the functional inspection. Emissions system defects identified during the functional inspection are considered unhealthy for the air and result in an overall Smog Check failure.

Gold Shield Dealer: The Gold Shield Dealer station sub-type is a new car dealer in a Basic or Change of Ownership area and has the ability to smog enhanced area cars that are to be sold in their program area.

Gold Shield Station: The Gold Shield Station type has met certain performance criteria and performs CAP repairs. As of late 2007, Gold Shield stations are authorized to perform initial inspections on Directed Vehicles.

GP: The emissions level, or “cut point,” at which a vehicle fails as a Gross Polluter. The emissions of a gross polluter are typically at least twice as high as those of an ordinary failing vehicle. Repairs on a Gross Polluter must be verified at a Test-Only or Gold Shield station.

Gross Polluter: The emissions levels, or “cut points,” established for the highest-polluting vehicles. The emissions of a Gross Polluter are typically at least twice as high as those of an ordinary failing vehicle. Repairs on a Gross Polluter must be verified at a Test-Only or Gold Shield station.

Gross Vehicle Weight Rating (GVWR): Gross Vehicle Weight Rating is the weight of the vehicle plus the maximum load it is designed to carry. This differs from the vehicle’s Test Weight.

Hydrocarbons (HC) (PPM): Hydrocarbons are the component of fuels that produce energy. HC emissions from a vehicle are basically unburned fuel. High levels of HC emissions indicate incomplete fuel combustion, either the result of a misfire or of low engine compression. Unhealthy levels of HC emissions result in a vehicle failing its Smog Check. Hydrocarbons are measured in parts per million (PPM).

Ignition Timing: The timing of the spark relative to the operation of the valves and the placement of the piston in the cylinder. BTDC stands for “before top dead center” a reference to a mark on the main pulley on the front of the engine. For most engines, when the timing is set to 0 degrees TDC, the number one piston will fire at the very top of the stroke. For vehicles where the manufacturer specifies a timing setting, the Smog Check inspection allows plus or minus three degrees from that setting. For vehicles where the manufacturer specifies a timing range, the vehicle must be within that timing range. Advanced timing is when the spark fires before the piston has reached the top of the stroke. Retarded timing is when the spark fires after the piston has reached the top

Inspection Reason: Either biennial (in conjunction with a DMV registration renewal notice), change of ownership (selling a car), or initial (first time registered in California).

License: The California license plate number on your vehicle. This field is left blank when there is no license plate on the vehicle.

Make: The vehicle manufacturer’s brand name.

MAX: The maximum allowable emissions for the particular make, model, and year of vehicle. Vehicles with emissions that exceed this level, or “cut point,” fail the emissions portion of the Smog Check. There are separate cut points for vehicles failing at ordinary vs. Gross Polluterlevels.

MEAS: The amount of each specific pollutant measured during the emissions test of the vehicle.

Model: The vehicle manufacturer’s model name.

Model-Year: The vehicle manufacturer’s model year for your vehicle. Not necessarily the year the vehicle was built.

NO (PPM): Oxides of nitrogen (more commonly called NOx) are odorless gases that help form smog, and give smog its characteristic brown color. NO is produced when temperatures in the combustion chambers exceed 2500 degrees Fahrenheit. Excessive engine temperatures could be caused by a lean fuel mixture, by retarded timing, by carbon buildup inside the combustion chamber, or by a malfunctioning engine cooling system. The function of the EGR System is to reduce NO. Unhealthy levels of NO emissions result in a vehicle failing its Smog Check. NO is measured in parts per million (PPM).

Odometer: The number of miles on your vehicle as reported by the technician based on his or her reading of your vehicle’s odometer.

Oxygen Sensor: A device located in the exhaust manifold or exhaust pipe which compares the level of oxygen in the ambient air to the level of oxygen in the exhaust stream and sends a signal to the vehicle’s onboard computer, which adjusts the fuel mix accordingly.

Parts Per Million (PPM): This is a unit of measurement for both Oxides of Nitrogen and Hydrocarbons which are measured by the BAR97 emissions analyzer.

Pass: The level of harmful emissions from this vehicle, on this portion of the test, is within the range of what is reasonable for this model/engine combination. Thank you for doing your part to improve our air quality to healthy levels in California.

Positive Crankcase Ventilation (PCV): Positive Crankcase Ventilation removes gases blown around the pistons and rings from the engine crankcase, and reroutes them through the intake manifold to be burnt again.

Regular Test and Repair: The Regular Test and Repair Station type performs inspections and repairs all types of vehicles. This station type does not have the ability to certify directed (Test Only) vehicles or vehicles with emissions in the gross polluter range.

Revolutions Per Minute (RPM): Revolutions per minute is a measurement of engine speed. Engine turning speed typically does not correspond to the speed of the vehicle.

Repair Tech Name / Number: The name of the licensed Smog Check technician who repaired the vehicle, if applicable or known.

Smog Check Certificate Number: This is the number of the electronic certificate sent to the Department of Motor Vehicles (DMV) which allows the owner to complete his or her registration. The Vehicle Inspection Report is proof of the vehicle passing a Smog Check.

Software Version / EIS Number: The BAR-certified version of the software that the emissions analyzer unit used during the test, and the unique identification number for the analyzer unit.

State: The state where the vehicle is registered.

Station Number: The license number of the Smog Check station where the test was performed.

System Malfunction Light: Also known as the “check engine light,” this early warning signal in the vehicle cabin indicates engine problems. Such problems could cause serious performance or engine problems for the vehicle if not checked and repaired, and could lead to excessive amounts of pollution being emitted during certain driving conditions which may not be detected during a Smog Check.

Test: The Acceleration Simulation Mode (BAR-97) test measures vehicle emissions levels at 15 mph and 25 mph with driving conditions simulated by the dynamometer, a treadmill-like device. The two-speed idle (TSI or BAR-90) test measures the emissions levels of a stationary vehicle at two engine idle speeds.

Test Only: The Test Only station type has the ability to test and certify all vehicles, though it cannot perform any repairs.

Test Weight: The actual weight of your vehicle as measured during the Smog Check.

Thermostatic Air Cleaner: Draws warm air into a cold engine to help fuel vaporize before burning. This system is important before the engine warms up, to improve cold drivability and cold-engine emissions reductions.

Transmission: Either manual (3-, 4-, 5-, or 6-speed) or automatic.

Type: Vehicles eligible for the Smog Check program include passenger cars, light-duty trucks and heavy-duty trucks.

VacuumLines to Sensors/Switches: A visual inspection of the vacuum lines to the sensors and switches in all of the emission control systems on the vehicle is performed. The technician will either pass or fail the these components based on observations made during the test.

Vehicle Identification Number (VIN): Your vehicle’s unique identification number, usually 17 digits but sometimes less. Typically found on the top of the dash just inside the windshield on the driver’s side, or on a plate/sticker in the driver’s side door jamb. The BAR code on your DMV registration renewal also contains this number. Contact the DMV if the VIN on your vehicle does not match the VIN on your registration form.

Visual Inspection: The first of the three vital parts of the California Smog Check. The visual inspection checks for missing, disconnected, or visibly damaged emissions-system components, including the catalytic converter, the thermostatic air cleaner, the heat riser and the smog pump. Emissions system defects identified during the visual inspection are considered unhealthy for the air and result in an overall Smog Check failure.

VLT Record #: Your vehicle’s record on the Bureau of Automotive Repair’s Vehicle Lookup Table (VLT). The table contains specific information for each vehicle model and engine combination available. Information from the VLT regarding your vehicle’s weight and aerodynamic resistance allows the Smog Check emissions analyzer to correctly set the resistance on the dynamometer (a treadmill-like device used to test vehicles in the smoggiest urban areas of the state).

Wiring to Sensors/Switches: A visual inspection of the wiring to the sensors and switches in all of the emission control systems on the vehicle is performed. The technician will either pass or fail the these components based on observations made during the test.

During the emissions test, the vehicle is driven on a dynameter (machine to allows the vehicle’s wheels to actually spin) while the smog machine collects and analyzes emissions coming from the tailpipe. The three main emissions measured are HC (Hydrocarbon), CO (Carbon Monoxide), and NOx (Nitrogen Oxide). When the vehicle is not burning gas efficiently, it will produce emissions levels higher than that set by California.

The emissions test is usually the part of the Smog Check where most vehicles fail.

Perform routine tune ups by changing the motor oil, spark plugs, fuel filter, and air filter. Regular maintenance can greatly improve your vehicles emission output by cleaning out engine oil contamination high in hydrocarbons. Most important, doing so will increase the vehicle’s ability to pass the smog check.

Read more about smog in Smog Check Frequently Asked Questions

Visual Test

The smog check technician will inspect various components of the engine to ensure that they are properly and securely connected. These components include:

• Underhood Emission Label
• Charcoal Canister (Evaporation Control System)
• Oxygen Sensor (O2 Sensor)
• Exhaust Gas Recirculation Valve (EGR)
• Positive Crankcase Ventilation Valve (PCV)
• Catalytic Converter
• Air Injection System

If possible, check the connections of these components at home prior to driving the smog check station. Verify that they are fully and firmly connected and not visually worn down.

Functional Test

The smog technician will test the following engine components to ensure that they are working properly.

• Check Engine LightThe smog check technician will look to see if the vehicle’s check engine indicator or light is on. If it is on, the vehicle fails the Smog Check automatically. Please ensure that it is off before going to the smog check station. If it is on, visit a chain auto supply store to get information on why the check engine light is on.
• Engine Ignition TimingThe smog check technician will check whether the vehicle’s ignition system is supplying correct electric current to the spark plugs and at the correct intervals.
• Gas Cap & Filler NeckThe vechicle’s gas cap will be checked to ensure that it holds the correct pressure and inhibits the gas fumes from escaping into the atmosphere. If the gas cap is malfunctioning, you may purchase a new gas cap from the smog check station. The filler neck will also be examined to ensure that it accepts and connects tightly with the correct gas cap.
• Exhaust Gas Recirculation ValveThe Exhaust Gas Recirculation Valve works by allowing a small amount of exhaust gas to recirculate back into the combustion chamber when the engine is prone to producing nitrogen oxides. Since exhaust gas cannot be burned again, combustion temperatures are reduced and, thus, the production of NOx is decreased. Because the EGR performs this important emissions reducing function, it is essential to ensure that this component is working properly. The EGR value is easily replaced and most replacements are available at the local auto parts store.
• Low Fuel Pressure Evaporative Test (LPFET)On December 1, 2007, California Bureau of Automative Repair added the EVAP Functional Test (LPFET) to test vehicles manufactured from 1976 to 1995 including all pre OBDII. The test is performed on the gas filler neck as well.