This page will answer or help you under stand what to do if the a vehicle comes into your shop for a smog inspection, and during your inspection you notice it has a gasoline fuel system that use to be a Diesel.

You should know do to proceed or what will you need to do to complete the smog inspection correctly.

Listed below is a chart on the correct procedures to help you to perform a legal smog check or to make aware to the customer if / he has any illegal equipment on the vehicle. 

It also will help you confirm if the modifications to the vehicle are legal. 

This information will be very help if you are trying to pass the state smog examination to become a smog inspector. 


Air Induction

Air Cleaner / Assembly – 1995 model-year and older without Thermostatic Air Cleaner. Changes are acceptable provided all required emission controls are connected.

Gasoline or Diesel vehicles do not require an EO number verification 

Air Cleaner / Assembly – 1996 model-year and newer and all years equipped with Thermostatic Air Cleaner

Gasoline vehicles do require an EO number verification 

Air Flow Sensor 

Gasoline and Diesel vehicles require an EO number

Intake Manifold – including diesel air horn or elbow

No EO number requires

Intercooler - Equipped with the original equipment turbocharger/ supercharger

Diesel vehicles require an EO number

Turbocharger/Supercharger - Wastegate, pulleys, etc

Diesel and gasoline vehicles an EO number

imagine by Mr. Lopez


Computer Management

Variable or Alternate Tuning Devices - “Modules,” “Chips,” “PROMs” “Tuners,” “Pods,” or any device that modifies or conditions ECU inputs or outputs.

Including, but not limited to, devices that plug into the ECU, wiring harness, or the OBD connector. (DLC plug-in telemetry or read-only devices are allowed without EO).

Gasoline and Diesel requires a verification with an EO number


Exhaust System

Air Injection Rails - Minor configuration changes allowed

No EO verification required

EGR system modifications. (Aftermarket replacements do not require EO). 

Gasoline and Diesel requires a EO Verification

Diesel Engine Exhaust Brake

No EO Verification required

After-treatment Control(s) – Catalyst, Diesel Particulate filters (DPF), sensors(O2, NOx , pressure, temp.), Diesel Exhaust Fluid (DEF) system, etc.

Diesel and Gasoline vehicles require a EO verification 

Customized Exhaust on vehicles without after-treatment components, or installed after last required “Cat-Back”- Crossover pipes, Oversized pipes, etc.

No EO verification required

Customized Exhaust before last required after-treatment component – Header 5 Heat Risers, Oversized pipes, etc. 

Diesel and gasoline vehicles require an EO number

Fuel System

Added or Alternative Fuel Kits – Nitrous, propane, methanol, hydrogen, natural gas Biodiesel4 , etc. 

Gasoline and Diesel vehicles require an  EO number 

Carburetor - Changes not originally offered for the specific vehicle application, i.e. changing: 2 to 4 barrel, 4 to 2 barrel, single to multiple carb, carb to fuel inj. Replacement carbs are okay when identified as such by the manufacturer.

Gasoline and Diesel vehicles require a EO number

Carburetor Related- Choke Heat Stove for Headers, Under carburetor screen

No EO number required

Fuel System- Adjustable fuel pressure regulators, Injectors, Injection pump. 

Gasoline and Diesel vehicles require a EO number

Fuel System- Diesel Lift Pump, Fuel Filters, Separators, fuel line magnets

No EO number required

Fuel Tank(s) - Additional, Oversized

Gasoline requires a EO number

Water Injection - Vapor / Steam

No EO number required

Ignition (Gasoline vehicles)

Ignition Bridge

No EO number is required

Ignition System Modification – Performance distributors, control modifications, etc. 

Gasoline vehicles require a EO number


Air Conditioner Cut-Out

No EO number verification required

Anti-theft System - Primary ignition changes including engine start / stop controls

No EO number required

Camshaft - Performance camshafts, adjustable gears, etc

Gasoline and Diesel are  requires a EO number

Engine Modifications- Performance kits, cylinder head swaps, etc

Gasoline and Diesel vehicles require a EO number


No EO number required

Hybrid Battery Enhancements- Plug-in charger kits, added batteries, etc.

No EO number required

Hose(s) - Minor configuration changes are acceptable. Universal replacement hose in place of preformed hose, etc

No EO number required

Oil Separator / Filter - Crankcase gas filter

No EO number required

Throttle lockout system

No EO number required

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Emission Control 1:

B.A.R. Smog Check

Inspector Level 1

(Inspector "Smog" License):

Engine Fundamentals  

8am - 12:15 pm 

Summer Class

7/5/2022 -8/5/2022

Class # 799065

Emission Control 2:

B.A.R. Smog Check

Inspector Level 2

(Inspector "Smog" License):

Rules and Regulations

8am - 12:15 pm

Summer Classes

7/5/2022 - 8/5/2022

Class # 799067

Engine Performance 1:

 8am - 12: 15 pm

Date: TBD

Class # 799069

Engine Performance 2:

B.A.R. Specified Diagnostic

and Repair Training

(Repair "Smog" License)

Time: TBD 

Date: TBD 

Class # 799071

Emission Control 1

(Inspector "Smog" License):

5:00pm - 8:45 pm

Date: TBD

Class # 799065

Emission Control 2: 

(Inspector "Smog" License):

5:00pm - 8:45 pm

Date: TBD

Class # 799065

Exhaust Emissions (Update Class):

5:30 pm - 8:45 pm 

Tuesday nights: 

Dates: coming soon 

Class # 796070