Catalytic converter
Cleans the exhaust. Required to pass California smog.
Signs it's worn: Rattle underneath, rotten-egg smell, P0420 code.
What's wrong with my car? · Exhaust
Rotten-egg smell, or a P0420 code?
Usually: Catalytic converter.
A rotten-egg smell, a P0420 code or a rattle from under the middle of the car points at the converter. Rule out O2 sensors first, they're far cheaper.
The parts that fix it
Oxygen sensor
Reads the exhaust so the computer can mix fuel correctly.
Signs it's worn: Check-engine light, bad mileage, failed smog check.
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