Exhaust Exhaust Emissions & Catalytic Converters

Question 1

What is the primary function of a catalytic converter in a vehicle's exhaust system?

Accepted Answer

To reduce harmful exhaust emissions

Answer

A catalytic converter uses chemical reactions to convert harmful pollutants like CO, NOx, and hydrocarbons into less harmful substances.

Question 2

Which of the following gases is NOT typically targeted for reduction by a three-way catalytic converter?

Accepted Answer

Carbon dioxide (CO2)

Answer

Three-way catalytic converters target CO, NOx, and unburned hydrocarbons; CO2 is a byproduct of complete combustion and is not reduced by the converter.

Question 3

What precious metal is most commonly used in catalytic converters to facilitate oxidation reactions?

Accepted Answer

Platinum

Answer

Platinum is the primary catalyst used in oxidation reactions within catalytic converters, alongside palladium and rhodium.

Question 4

The OBD-II system monitors catalytic converter efficiency primarily using which sensor?

Accepted Answer

Downstream oxygen sensor

Answer

The downstream (post-cat) oxygen sensor compares its readings to the upstream sensor to determine if the catalytic converter is functioning efficiently.

Question 5

Which emission standard, introduced federally in the US, requires vehicles to meet strict NOx and particulate limits?

Accepted Answer

Tier 3

Answer

The EPA's Tier 3 emission standards, phased in from 2017, require significant reductions in NOx and particulate matter from new vehicles sold in the US.

Exhaust Practice Test

Exhaust Practice Test

Exhaust Exhaust Emissions & Catalytic Converters