Answers to Frequently Asked Questions about the new Diesel Smog Check Program and the Diesel Vehicle Smog Test starting in Jan. 2010

Information for Diesel Vehicle Owners and Smog Technicians on the Diesel Smog Check Inspection Program


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Here is the Nitty Gritty of the Diesel Smog Inspection Law and the Diesel Smog Test Proceedure in its Official Form ( to date)


Overview of AB 1488 l Assembly Bill 1488 (Mendoza, Chapter 739, Statutes of 2007) requires:

l Model year 1998 and newer diesel-powered vehicles be included in the Smog Check Program FD

Change of Ownership inspections FD

Out of State vehicles l Under 14,000 lbs GVWR

Testing begins January 2010

Statewide implementation of diesel testing l ARB/BAR to develop inspection procedures

DMV registration renewal notices will indicate whether an inspection is required.

DMV will begin notification January 2010 (This is incorrect as I have personally experienced Diesel Vehicle owners already being notified and seen the renewal Forms with Smog Inspection Required Statement as early as June of 09)

Diesel change-of-ownership will require inspections beginning January 2010

Approximately half of the diesel vehicles subject to inspection will obtain a Smog Check each year. FD Initial biennial split FD Change of Ownership effects

AB 1488, Mendoza. Air pollution: smog check program: diesel-powered vehicles.

(1) Existing law establishes a motor vehicle inspection and maintenance program (smog check), administered by the Department of Consumer Affairs and the State Air Resources Board, that provides for the inspection of all motor vehicles, except those specifically exempted from the program, upon registration, biennially upon renewal of registration, upon transfer of ownership, and in certain other circumstances. Existing law also establishes an enhanced motor vehicle inspection and maintenance program (smog check II) in each urbanized area of the state, any part of which is classified by the United States Environmental Protection Agency as a serious, severe, or extreme nonattainment area for specified air contaminants. Existing law also requires the smog tests to include, at minimum, loaded mode dynamometer testing in enhanced areas, and 2-speed testing in all other program areas, and a visual or functional check of emission control devices specified by the department. Existing law exempts diesel-powered vehicles from these requirements, unless the department determines that the inclusion of those vehicles is technologically and economically feasible, and, if the department makes that determination, requires a visual inspection of emission control devices and the diesel-powered vehicle's exhaust emissions, and authorizes the testing of emissions of specified pollutants and the measurement of emissions of smoke or particulates, or both. Violations of smog check requirements are a crime.

This bill would, starting January 1, 2010, include diesel-powered vehicles manufactured after the 1997 model-year that have a gross vehicle weight rating of less than 8,501 pounds in the biennial smog check program, as provided.

The bill would authorize diesel-powered vehicle smog check testing to include on-board diagnostic testing. and Visible Smoke Checks

These are the DRAFT Recomendations of the BAR, for the Diesel Vehicle Inspection Procedures as of January 20 2009 found here Diesel Smog Check Procedure in a printable .pdf form

Based on the informantion gathered from the vehicle testing performed during the joint ARB/BAR study on diesel vehicles subject to the smog cheak program, recommended test procedures were developed for visual checks of required emission control devices, an OBD check and a visible smoke test. The following test procedures are recommended.

I Visual Checks:

Technicians shall conduct visual checks in accordance with the inspection procedures described in the Smog Check Inspection Manual and as prompted by the EIS

Step 1 : Technicians must use all available information necessary to determine the vehicles emission control requirements, including but not limited to, the under-hood emission control lavel, a current emission control application guide, emission control repair manuals, emission component location guides, manufacturer emission control recalls, vacuum/pressure hose routing diagrams, Air Resources Board (ARB) aftermarket parts listings, the aftermarket part label, and any reliable vehicle manufacturer sources.

Step 2 : If a vehicle is equiped with parts that modify the original emission control configureation, technician must verify whether those Parts are ARB approved or exempted.(Not all aftermarket parts modify the original emission control configuration and therefore do not require ARB approval or exemption. For more information see the Aftermarket Parts Verification Guidelines included in the Smog Check Reference Guide, and or the ARB website, as described below). If the installed Parts are not ARB approved or exempted, and the original emissions control configuration has been modified, the corresponding emissions controld are considered m"Modified" and the vehicle shall fail the inspection.

Step 3 : To Verify ARB approval or exemption, technicians must check the Aftermarket Parts Label affixed either directly to the part or near the part. This Label contains ARB Executive Order (EO) that can be used to verify approval or exemption. With the EO number, reference the ARB EO parts listings and/or part manufacurer catalog. The ARB EO parts listings contain information about parts with ARB EO numbers, the part manfacturers, and the applicable vehicles on which the parts can be installed. The ARB EO part listings can be found on the ARB website found at www. arb.ca.gov then choose "Aftermarket Parts". The ARB aftermarket parts listings may also provide information about modifications that are necessary and acceptable for installation of a particular part, kit or system.

Step 4 : If the aftermarket part label is missing ot illegible, the technician may proceed with the inspection, provided the parts can be confirmed as ARB approved or exempted by comparing the part number marked on the part with the ARBEO parts listings, or the parts manufacturer's catalog.

Step 5 : Technicians must inspect the emission control systems as listed in Table 1 and enter the inspection results as prompted by the EIS. Check that each system is complete and installed per the vehicle manufacturer's original configuration or, when applicable, an ARB-approved aftermarket configuration.

Sep 6 : If any required emission control systems are found to be tampered or defective, the vehicle shall fail the inspection.

Tabel 1

BAR-97 Diesel Inspection Components

Use the existing BAR-97 inspection prompts... ...to record the visual inspection results of these Diesel ECS
Positive Crankcase Ventilation (PCV)
Crankcase Depression Regulator (CDR) or PCV
Catalytic Converter
Diesel Oxidation Catalyst (DOC) OR (OC)
Diesel Particulate Filter (DPF)
Periodic Trap Oxidizer (PTOX)
NOX Adsorber Catalyst
Selective Catalytic Reduction (SCR - Urea Injection)
Exhaust Gas Recirculation ( EGR )
Diesel EGR
Fuel Injection
Diesel Fuel Injection ( DFI )
Oxygen Sensor and Connectors
Pressure sensors, temperature sensors, and Lambda (Oxygen) Sensors
Wiring of Sensors/Switches/Computer
Wiring of Sensors/Switches/Computer
Vacuum Line Connections to Sensors/Switches
Vacuum Line Connections to Sensors/Switches
Other Emission-Related Components
Other Diesel Emission-Related Components
Turbo Charger (TC)/Supercharger, Cylinder Heads, Exhaust Manifolds, Intake Manifolds, Charge Air Cooler (CAC) and any other emissions-related components
Diesel Visable Smoke Test


II OBD Test (Including OBDII Scan)

Diesel Vehicles will be subject to the OBD tests. As with gasoline-powered CAN vehicles, diesel vehicles with the CAN protocol will be temporarily excluded from the OBD portion of the Inspection. The BAR-97 cannot perform the OBD scan for any vehicles with the newer Controller Area Network (CAN) OBD communication protocol.

On 1998-2003 diesel vehicles, performance of the OBD scan will be controlled by the BAR-97 software and the Vehicle Lookup Table (VLT). To prevent the vehicles from falsely failing the OBD scan, this process will rely on the technician to correctly identify the Certification Type (e.g.Federal or California) from the Vehicle Emission Control Information (VECI) label.

When the OBD test is performed the technicial shall:

Step 1: Determine that the dashboard MIL is operational by turning on the ignition key to the "ON" position with the engine turned off (i.e. not running). The MIL will illuminate if it is operational.

Step 2: The MIL then must be checked for a light "ON", indicating a failing condition. All OBDII-equiped vehicles that are compatible that can be checked by the BAR-97 must be connected to the EIS when prompted.

Step 3:Finally, MIL status, OBD readiness status codes, and DTCs will be downloaded to the BAR-97 and automatically evaluated by the software.

The vehicle shall fail Smog Check when failing any portion of the OBD test.


III Visable Smoke Test

Technicians shall use the following recommended visible smoke test proceedure when testing diesel-powered vehicles. The Visible Smoke Test proceedure consists of the following parts: General Test Proceedure

1. The Idle Test - With the engine at normal operating temperature, and running at idle. Observe the tailpipe exhaust plume of the vehicle for 10 seconds.

2. The Idle PCV/CDR Test - The technician shal get out of the vehicle with the engine idling, and look for visible smoke from the PCV/CDR system for 10 seconds.

3. The Snap Test - The technician shall push the accelerator pedal quickly from the idle position to between 2000 and 3000 RPM, then immediately release the accelerator pedal, allowing the engine to return to idle. For many vehicles you will be able to quickly push the accelerator pedal all the way to the floor and stay within the designated RPM range,(and observe the tailpipe for smoke )

4. Enter test results into the EIS.

5. Document any failure on the Vehicle Inspection Report (VIR) and the consumers invoice.


Specific Test Proceedures

When the technician performs the test, the following steps shall be followed:

Step 1 - Vehicle Preperation

Position the vehicle to ensure that there are no drafts that can disturb the exhaust plume that could artificially disperse smoke from the exhaust.

Turn off all auxiliary engine cooling fans that are used for ASM testing.

Verify the engine is at normal operating temperature.

Verify that all vehicle accessories, including Air conditioning are OFF.

Ensure that the transmission is in "Park" (Automatic Transmission) or "Neutral" Manual Transmission) with the parking brake set, and the wheels chocked.

Step 2 - Test Preperation and familiarization with the vehicle:

Setup any means necessary such as adjusting the seating position and the mirror position to observe the exhaust plume during the snap test, and become familiar with the accelerator pedal and engine response.

Perform the first of three snap tests as defined above in #3 "The Snap Test"

Check the vehicles engine RPM during the first snap test, If it does not fall between 2000 and 3000 RPM, you can do one of the following:

Press and relsease the accelerator pedal more quickly or more slowly as needed to stay within the designated RPM range; or

Quickly depress the pedal only part way to the floor before releasing it.

The technician shall ensure that the vehicle's engine speen does not exceed 3000 RPM.

The technician shall not check for smoke during the first nap test and, any visible smoke observed during the first snap test will not result in a failure.

Step 3 - Perform the Idle Test and Oserve the Tailpipe Smoke

With the engine at normal operating temperature and running at idle.

Go around to the vehicles tailpipe.

Observe the tailpipe exhaust plume of the vehicle for 10 seconds.

Step 4 - Idle Test of Crankcase (PCR/CDR) Smoke

Leave the vehicle's engine running at idle and go around to the vehicle engine compartment

Open the hood of the engine compartment, and locate any crankcase ares of concern.

Continuously watch the crankcase (PCV/CDR) system for 10 seconds.

Step 5 - Perform the Snap Test and Observe Tailpipe Smoke

When Prompted by the EIS for the "Other Emissions Related Components".

Using means necessary such as looking out the rear window of the vehicle or using the vehicle's rear view mirrors, watch for visible smoke coming from the tailpipe(s) exhaust plume each time the engine RPM is increased.

Perform the second of three Snap Tests as defined above in #3 "The Snap Test" , while watching for visible smoke.

Reurn to Idle, and wait at least one second, and no more than five seconds

Perform the third (and final) snap test as defined above in #3 "The Snap Test" , while watching for visible smoke.

Step 6 - PASS/FAIL Determination :

PASS - the vehicle for the visible smoke test portion of the inspection if the vehicle Passes all three smoke tests (Idle, Snap, and (PCV/CDR).

FAIL - the vehicle if:

There is any visible smoke during the idle test

OR there is any visible smoke coming from the (PCV/CDR) system

OR there is visible smoke plume coming from the vicinity of the tailpipe(s) exhaust plume on either of the last two snap tests AND the plume lingers for more than 3 seconds.

Smoke from any other area than the vehicles tailpipe(s) or PCV/CDR system regardless of the cause, does not constitue a failure of the Visible Smoke Test.

No Vehicle will be failed for steam. Steam is always white and usually evaporates quickly condenses, while smoke may dissipate but never evaporates.

Step 7 - Entering the test results into the EIS

For vehicles that meet the passing criteria above, enter "P" (Pass) in the "Other Emission Related Controls" category of the visual inspection portion of the Smog Check, when prompted by the EIS.

For vehicles that fail the visible smoke check according to the criteria above enter "F" (defective) in the "Other Emission Related Controls" category of the visual inspection portion, when prompted by the EIS.

Note: The EIS currently allows only one entry for the visual inspection of all components covered under the "Other Emission Related Controls" category. Therefore, if the vehicle passes the visible smoke test but fails a visual check of any component covered under the "Other Emission Related Controls" category, enter the appropriate failure code: "D" Disconnected) "M" (Modified) or "S" (Missing". However, if the vehicle passes the visual inspection for components including those in the "Other Emission Related Controls" category but fails the smoke test, enter "F" (Defective) into the EIS.

Step 8 - Documentation Provided to Consumer: If the Vehicle fails the Visible Smoke Test, the technicial shall:

Document the failure on the customers copy of the Vehicle Inspection Report (VIR) in the"Other Emission Related Controls" section. Make a clear notation on the VIR, such as "Failed for visible smoke" or "Failed visible smoke test" . Write down what part of the visible smoke test the vehicle failed, such as "Failed Crankcase Smoke", "Failed Idle Tailpipe Smoke" or "Failed Snap Tailpipe Smoke."

Document the failure on the customers invoice with "Failed for visible smoke" or "Failed visible smoke test" . Write down what part of the visible smoke test the vehicle failed, such as "Failed Crankcase Smoke", "Failed Idle Tailpipe Smoke" or "Failed Snap Tailpipe Smoke."

Provide the customer the Bureau's Diesel Test Consumer Information Sheet, with the applicable items completed on the checklist.





Here is what it means for you Diesel Car and Truck Owners in laymans terms, and I'll Give you the best tip to avoid failing right now.





What is a DTC ?

DTC= Diagnostic Trouble Code

[Most Repair Shops and Dealers can literally Pull the DTC's in less than 5 minutes, but they will usually CHARGE you an hour of labor to help pay for their Overhead and the cost of the Scan Tool or Equipment that is used to Read the Codes. ALL Test and Repair Smog Inspection Stations can also Pull the Codes and usually will Pull Codes for less than Dealers and Repair Shops ]


When does the Diesel Smog Check Program start and what vehicles will need to be tested?

Starting in Jan of 2010 :

1998 and newer Diesel Cars and Trucks are going to have a Biennual Smog inspection (just like gasoline powered cars and trucks do) and to sell your Diesel car or truck (or to bring a diesel car or truck into California and register it) it is going to need a Diesel Smog Inspection

What will We Check in a Diesel Smog Check ?

A visual inspection to verify that all original emissions equipment is still installed, and if there is aftermarket equipment installed to verify that it is CARB approved for the vehicle it is installed on and verify that the CARB Stickers for the equipment is present.

An OBD-II Check to see if the Check Engine light works

A Check Engine light should: come on when the ignition key is turned on and go out after the vehicle starts. If it stays on it fails, because there is problem and a DTC has been set

The OBD-II Test also Checks that there are sufficient OBD-II System Monitors Ready and working, and Checks to see if any DTC's are Present.


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