2 parts covered
The exhaust and emissions system routes exhaust gases away from the engine and cabin, reduces harmful emissions through catalytic conversion, and manages engine breathing through the EGR system and oxygen sensors.
The catalytic converter reduces harmful emissions by converting toxic exhaust gases (carbon monoxide, hydrocarbons, nitrogen oxides) into less harmful substances (carbon dioxide, water vapor, nitrogen). It's expensive because it contains precious metals (platinum, palladium, rhodium).
Total Cost
$1,000 – $3,000
Lifespan
100,000 – 200,000 miles
DIY Difficulty
If It Fails
Oxygen sensors measure the oxygen content in exhaust gases, telling the engine computer whether the air-fuel mixture is too rich (too much fuel) or too lean (too much air). Most cars have 2-4 oxygen sensors.
Total Cost
$100 – $350 per sensor
Lifespan
60,000 – 100,000 miles
DIY Difficulty
If It Fails