Exhaust Basics
What is the main purpose of the exhaust system?
To route exhaust gases safely away from the vehicle and reduce noise
What does HC stand for in emissions?
Hydrocarbons
What component converts harmful gases into CO₂, N₂, and H₂O?
Catalytic converter
What federal law established vehicle emission requirements in 1970?
Clean Air Act
What fuel property was reduced to lower PM emissions?
Sulfur content
Name two common exhaust components.
Exhaust manifold, muffler
Which emission gas is odorless, colorless, and deadly?
Carbon monoxide (CO)
What does the PCV system control?
Crankcase emissions (blow-by gases)
What agency enforces emission standards in California?
California Air Resources Board (CARB)
What does SCR use to reduce NOx emissions?
Diesel Exhaust Fluid (DEF)
What part of the exhaust system reduces engine noise?
Muffler
What two pollutants combine in sunlight to form smog?
HC and NOx
What component stores fuel vapors before they are burned?
EVAP/charcoal canister
What does a smog rating of 10 indicate?
Least polluting vehicle
What filter removes soot from diesel exhaust?
Diesel Particulate Filter (DPF)
What is the function of a resonator?
Absorbs additional sound vibrations
What pollutant is primarily responsible for acid rain?
Nitrogen oxides (NOx)
What sensor monitors oxygen levels in exhaust gases?
Oxygen sensor
What is the purpose of I/M testing?
To ensure vehicles meet emission limits
What process cleans a DPF when it is full of particles?
Active regeneration
Why is it critical to move exhaust away from the passenger cabin?
To prevent carbon monoxide poisoning
What greenhouse gas is produced by burning fuel?
Carbon dioxide (CO₂)
What component reduces NOx by recirculating exhaust gases?
Exhaust Gas Recirculation (EGR) valve
How long is the catalytic converter warranty under federal law?
8 years / 80,000 miles
Name two components unique to diesel emission systems.
Diesel Oxidation Catalyst (DOC) and Selective Catalytic Reduction (SCR)