CPT Emissions & Environmental Standards Flashcards
6 cards from real CPT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CPT Emissions & Environmental Standards flashcards as text
What is the purpose of secondary air injection (SAI) during cold engine startup in modern emission control systems?
Answer: To inject fresh air into the exhaust stream to oxidize HC and CO before the catalytic converter reaches operating temperature
Cold catalysts cannot oxidize emissions, so SAI injects air into the hot exhaust stream to burn off HC and CO chemically until the catalyst warms up.
On a diesel engine, what is the function of Diesel Particulate Filter (DPF) regeneration, and what triggers it?
Answer: Regeneration burns accumulated soot in the DPF using elevated exhaust temperatures, triggered when soot load exceeds a calibrated back-pressure or modeled threshold
DPF regeneration uses high exhaust temperatures to oxidize accumulated particulate matter into CO2 and water, initiated when the ECU detects excessive soot accumulation.
A diesel truck's Selective Catalytic Reduction (SCR) system requires Diesel Exhaust Fluid (DEF). What is DEF composed of and what emission does it reduce?
Answer: 32.5% urea in deionized water; it reduces NOx by converting it to nitrogen and water over the SCR catalyst
DEF is a 32.5% urea/water solution that hydrolyzes to ammonia, which reacts with NOx over the SCR catalyst to produce harmless nitrogen and water.
When a CPT technician installs an aftermarket performance exhaust that meets OEM pipe diameter requirements but removes the catalytic converter on a street car, which federal penalty applies to the shop?
Answer: Civil penalties under Clean Air Act Section 203, which prohibits tampering with emission control devices
CAA Section 203 prohibits any person from removing or rendering inoperative emission control devices on vehicles used on public roads, with civil penalties up to $44,539 per violation.
What does the OBD-II parameter 'catalyst temperature' bank 1 sensor 1 monitor, and how does it relate to emission compliance?
Answer: It estimates the temperature of the catalytic converter to confirm it has reached light-off temperature for efficient emission reduction
Catalyst temperature monitoring confirms the converter has reached its light-off temperature (~300°C) needed for efficient HC, CO, and NOx conversion.
A CPT technician tunes a competition vehicle exempt from road use emissions laws. Which US agency's regulations would still apply to the tuning facility itself regarding volatile organic compound (VOC) emissions from solvents and paints used in the shop?
Answer: The EPA's National Emission Standards for Hazardous Air Pollutants (NESHAP) and state/local air quality management districts
Shop operations using paints, solvents, and cleaning agents are regulated under NESHAP and state air quality rules for VOC and HAP emissions regardless of vehicle exemption status.