CPT CPT Emissions & Environmental Standards

Question 1

Under US EPA regulations, what is the primary purpose of the On-Board Diagnostics II (OBD-II) system in relation to emissions?

Accepted Answer

To continuously monitor emission-related components and alert the driver via the MIL when thresholds are exceeded

Answer

OBD-II continuously monitors emission-related systems and illuminates the MIL when a fault could cause emissions to exceed 1.5 times the applicable standard.

Question 2

Which exhaust gas component is the primary indicator of catalytic converter efficiency during an emissions test?

Accepted Answer

Hydrocarbons (HC)

Answer

Hydrocarbons indicate unburned fuel passing through the catalyst; a functioning converter oxidizes HCs to CO2 and H2O, so high HC levels indicate converter failure.

Question 3

A vehicle fails an I/M 240 emissions test with high NOx readings. Which engine operating condition is MOST responsible for elevated NOx production?

Accepted Answer

Excessively lean air-fuel mixture combined with high combustion temperatures

Answer

NOx forms when nitrogen and oxygen react at very high temperatures — lean mixtures burn hotter and promote NOx formation.

Question 4

What is the three-way catalytic converter (TWC) designed to simultaneously reduce?

Accepted Answer

Hydrocarbons (HC), Carbon Monoxide (CO), and Nitrogen Oxides (NOx)

Answer

A three-way catalyst oxidizes HC and CO while simultaneously reducing NOx, requiring near-stoichiometric operation to function efficiently.

Question 5

Under California CARB regulations, what is the significance of a vehicle being classified as a PZEV (Partial Zero Emission Vehicle)?

Accepted Answer

It meets near-zero tailpipe emissions standards and has zero evaporative emissions with a 15-year/150,000-mile emission warranty

Answer

PZEV certification requires extremely low tailpipe emissions, zero evaporative emissions, and an extended 15-year/150,000-mile warranty on emission components.

CPT - Certified Performance Technician Practice Test

CPT - Certified Performance Technician Practice Test

CPT CPT Emissions & Environmental Standards