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Texas Vehicle Emissions Inspector Licensing Exam
QUESTIONS AND DETAILED SOLUTIONS JUST
RELEASED
Texas Vehicle Emissions Inspector License Exam
Based on official Texas Department of Public Safety (DPS) guidelines, the Emissions Inspector exam is
administered as part of the vehicle inspector licensing process. It covers the OBD II emissions inspection
procedure, vehicle applicability, Malfunction Indicator Light (MIL) requirements, readiness monitors,
waivers, and safety inspection integration .
Part 1: Exam Coverage Summary (Point Form)
I. Program Overview & Air Quality
• Motor vehicles are the largest source of HC (hydrocarbons) and CO (carbon monoxide) in Texas
• Primary contributor to ground-level ozone (smog): Hydrocarbons (HC) reacting with oxides of
nitrogen (NOx)
• A "typical" vehicle emits about 1/2 ton of air pollution annually
• Malfunctioning vehicles emit many times that amount
• Primary purpose of OBD II: Ensure vehicles emit minimum level of pollutants through their
useful life
II. Affected Counties & Applicability
• 17 affected counties in Texas: Brazoria, Collin, Dallas, Denton, Ellis, El Paso, Fort Bend,
Galveston, Harris, Johnson, Kaufman, Montgomery, Parker, Rockwall, Tarrant, Travis,
Williamson
• Designated vehicle: Gasoline-powered, 2-24 years old, registered in/primarily operated in an
affected county
• Exempt vehicles: Diesel-powered, electric vehicles (EVs), motorcycles, slow-moving vehicles
(<25 mph)
III. OBD II System Requirements
• Required on all 1996 or newer gasoline-powered vehicles with GVWR of 8,500 lbs or less
• Vehicles with GVWR over 8,500 lbs are NOT required to have a DLC; but if equipped, connect to
it
• DLC location: Beneath instrument panel, near steering column (between driver's end and 1 ft
beyond centerline)
IV. Malfunction Indicator Light (MIL)
• Official term: Malfunction Indicator Light (NOT "Maintenance Light" or "Check Engine" — those
are displays)
• Amber in color; purpose: alert driver to malfunction for timely repairs
• Flashing MIL: Indicates severe misfire that could damage catalytic converter; intended to
discourage operation
• Steady/constant MIL: Problem detected that could cause emissions to exceed 1.5x standard;
service as soon as possible
• KOEO check: MIL must illuminate when key is turned on, engine off; brief illumination then off is
acceptable
• KOER check: After start, if MIL on, fail; if off, pass (unless commanded on by PCM)
V. Readiness Monitors
• "Ready" = component was tested by OBD II system
• "Not ready" = battery disconnected, codes cleared, or insufficient drive cycle
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• 1996-2000 vehicles: Fail if more than 2 monitors set to "Not Ready"
• 2001 and newer: Fail if more than 1 monitor set to "Not Ready"
• Vehicle does NOT need to be warmed up for OBD II inspection
VI. Fuel Cap Test
• Required for gasoline-powered vehicles 2-24 years old
• Exempt: Motorcycles, slow-moving vehicles (<25 mph), vehicles newer than 2 years or older
than 24 years
• Perform test twice if cap fails first time
VII. Waivers
• Individual Vehicle Waiver – used in Texas inspection program
• Low Mileage Waiver – used in program
• Low Income/Time Extension Waiver – used in program
• Vehicle must pass safety inspection at a DPS waiver station to qualify for waiver
VIII. ASM (Acceleration Simulation Mode) Testing
• For 1995 and older designated gasoline vehicles in most affected counties
• Uses dynamometer and 5-gas analyzer (measures HC, CO, CO₂, O₂, and NOx)
• Never operate dynamometer without restraining vehicle first
• Do not operate in reverse (except removal) or slam brakes when wheels in motion on
dynamometer
• Reject vehicles with excessive fluid leaks, space saver tire on drive axle, or damaged/worn tires
IX. TSI (Two-Speed Idle) Testing
• Used in El Paso, Travis, Williamson counties for 1995 and older vehicles
• Cannot evaluate NOx because vehicle not under load
• Does not identify as many HC/CO problems as ASM test
Program Overview & Air Quality (1-20)
Question 1
Which statement best explains the primary purpose of the Texas vehicle emissions inspection program?
A) To increase state revenue through inspection fees
B) To ensure vehicles are safe and meet emissions standards
C) To reduce insurance costs for Texas drivers
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D) To promote new vehicle sales
Answer: B
Rationale: The inspection program exists to ensure safety and environmental compliance, not revenue or
sales .
Question 2
Motor vehicles are the largest source of which two pollutants in Texas?
A) Carbon dioxide and sulfur dioxide
B) Hydrocarbons (HC) and Carbon Monoxide (CO)
C) Lead and mercury
D) Particulate matter only
Answer: B
Rationale: Motor vehicles are the largest source of hydrocarbons (HC) and carbon monoxide (CO) in
Texas .
Question 3
A "typical" motor vehicle emits approximately how much air pollution annually?
A) 100 pounds
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B) 500 pounds (1/4 ton)
C) 1,000 pounds (1/2 ton)
D) 2,000 pounds (1 ton)
Answer: C
Rationale: A "typical" vehicle emits about a half ton (1,000 pounds) of air pollution annually .
Question 4
What is formed by atmospheric reaction between hydrocarbons (HC) and oxides of nitrogen (NOx)?
A) Carbon monoxide
B) Ground-level ozone (smog)
C) Sulfuric acid
D) Particulate matter
Answer: B
Rationale: Ozone is formed by atmospheric reaction between hydrocarbons (HC) and oxides of nitrogen
(NOx), which are the main causes of urban smog .
Question 5
Which statement about a malfunctioning vehicle is TRUE?
Texas Vehicle Emissions Inspector Licensing Exam
QUESTIONS AND DETAILED SOLUTIONS JUST
RELEASED
Texas Vehicle Emissions Inspector License Exam
Based on official Texas Department of Public Safety (DPS) guidelines, the Emissions Inspector exam is
administered as part of the vehicle inspector licensing process. It covers the OBD II emissions inspection
procedure, vehicle applicability, Malfunction Indicator Light (MIL) requirements, readiness monitors,
waivers, and safety inspection integration .
Part 1: Exam Coverage Summary (Point Form)
I. Program Overview & Air Quality
• Motor vehicles are the largest source of HC (hydrocarbons) and CO (carbon monoxide) in Texas
• Primary contributor to ground-level ozone (smog): Hydrocarbons (HC) reacting with oxides of
nitrogen (NOx)
• A "typical" vehicle emits about 1/2 ton of air pollution annually
• Malfunctioning vehicles emit many times that amount
• Primary purpose of OBD II: Ensure vehicles emit minimum level of pollutants through their
useful life
II. Affected Counties & Applicability
• 17 affected counties in Texas: Brazoria, Collin, Dallas, Denton, Ellis, El Paso, Fort Bend,
Galveston, Harris, Johnson, Kaufman, Montgomery, Parker, Rockwall, Tarrant, Travis,
Williamson
• Designated vehicle: Gasoline-powered, 2-24 years old, registered in/primarily operated in an
affected county
• Exempt vehicles: Diesel-powered, electric vehicles (EVs), motorcycles, slow-moving vehicles
(<25 mph)
III. OBD II System Requirements
• Required on all 1996 or newer gasoline-powered vehicles with GVWR of 8,500 lbs or less
• Vehicles with GVWR over 8,500 lbs are NOT required to have a DLC; but if equipped, connect to
it
• DLC location: Beneath instrument panel, near steering column (between driver's end and 1 ft
beyond centerline)
IV. Malfunction Indicator Light (MIL)
• Official term: Malfunction Indicator Light (NOT "Maintenance Light" or "Check Engine" — those
are displays)
• Amber in color; purpose: alert driver to malfunction for timely repairs
• Flashing MIL: Indicates severe misfire that could damage catalytic converter; intended to
discourage operation
• Steady/constant MIL: Problem detected that could cause emissions to exceed 1.5x standard;
service as soon as possible
• KOEO check: MIL must illuminate when key is turned on, engine off; brief illumination then off is
acceptable
• KOER check: After start, if MIL on, fail; if off, pass (unless commanded on by PCM)
V. Readiness Monitors
• "Ready" = component was tested by OBD II system
• "Not ready" = battery disconnected, codes cleared, or insufficient drive cycle
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• 1996-2000 vehicles: Fail if more than 2 monitors set to "Not Ready"
• 2001 and newer: Fail if more than 1 monitor set to "Not Ready"
• Vehicle does NOT need to be warmed up for OBD II inspection
VI. Fuel Cap Test
• Required for gasoline-powered vehicles 2-24 years old
• Exempt: Motorcycles, slow-moving vehicles (<25 mph), vehicles newer than 2 years or older
than 24 years
• Perform test twice if cap fails first time
VII. Waivers
• Individual Vehicle Waiver – used in Texas inspection program
• Low Mileage Waiver – used in program
• Low Income/Time Extension Waiver – used in program
• Vehicle must pass safety inspection at a DPS waiver station to qualify for waiver
VIII. ASM (Acceleration Simulation Mode) Testing
• For 1995 and older designated gasoline vehicles in most affected counties
• Uses dynamometer and 5-gas analyzer (measures HC, CO, CO₂, O₂, and NOx)
• Never operate dynamometer without restraining vehicle first
• Do not operate in reverse (except removal) or slam brakes when wheels in motion on
dynamometer
• Reject vehicles with excessive fluid leaks, space saver tire on drive axle, or damaged/worn tires
IX. TSI (Two-Speed Idle) Testing
• Used in El Paso, Travis, Williamson counties for 1995 and older vehicles
• Cannot evaluate NOx because vehicle not under load
• Does not identify as many HC/CO problems as ASM test
Program Overview & Air Quality (1-20)
Question 1
Which statement best explains the primary purpose of the Texas vehicle emissions inspection program?
A) To increase state revenue through inspection fees
B) To ensure vehicles are safe and meet emissions standards
C) To reduce insurance costs for Texas drivers
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D) To promote new vehicle sales
Answer: B
Rationale: The inspection program exists to ensure safety and environmental compliance, not revenue or
sales .
Question 2
Motor vehicles are the largest source of which two pollutants in Texas?
A) Carbon dioxide and sulfur dioxide
B) Hydrocarbons (HC) and Carbon Monoxide (CO)
C) Lead and mercury
D) Particulate matter only
Answer: B
Rationale: Motor vehicles are the largest source of hydrocarbons (HC) and carbon monoxide (CO) in
Texas .
Question 3
A "typical" motor vehicle emits approximately how much air pollution annually?
A) 100 pounds
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B) 500 pounds (1/4 ton)
C) 1,000 pounds (1/2 ton)
D) 2,000 pounds (1 ton)
Answer: C
Rationale: A "typical" vehicle emits about a half ton (1,000 pounds) of air pollution annually .
Question 4
What is formed by atmospheric reaction between hydrocarbons (HC) and oxides of nitrogen (NOx)?
A) Carbon monoxide
B) Ground-level ozone (smog)
C) Sulfuric acid
D) Particulate matter
Answer: B
Rationale: Ozone is formed by atmospheric reaction between hydrocarbons (HC) and oxides of nitrogen
(NOx), which are the main causes of urban smog .
Question 5
Which statement about a malfunctioning vehicle is TRUE?
