ASE4 Emission Control Systems

Question 1

The EGR (Exhaust Gas Recirculation) system primarily reduces which exhaust emission?

Accepted Answer

Oxides of nitrogen (NOx)

Answer

Hydrocarbons (HC)

Answer

Carbon monoxide (CO)

Answer

Carbon dioxide (CO2)

Question 2

A stuck-open EGR valve at idle will cause:

Accepted Answer

Rough idle and possible stalling

Answer

Increased NOx emissions

Answer

Rich air/fuel mixture at idle

Answer

Increased engine power

Question 3

The EVAP (Evaporative Emission Control) system is designed to:

Accepted Answer

Prevent fuel vapor from escaping to the atmosphere

Answer

Reduce NOx emissions from combustion

Answer

Cool the catalytic converter

Answer

Recirculate exhaust gases

Question 4

A P0442 code (small EVAP leak detected) is set. The FIRST step in diagnosis is:

Accepted Answer

Perform a smoke test to locate the leak source

Answer

Replace the purge solenoid

Answer

Replace the fuel cap

Answer

Replace the EVAP canister

Question 5

An oxygen sensor that switches slowly between rich and lean is described as:

Accepted Answer

Lazy or degraded

Answer

Biased rich

Answer

Normal for a warm sensor

Answer

Cross-counting correctly

Question 6

During a catalyst monitor drive cycle, the downstream O2 sensor switches as frequently as the upstream sensor. This indicates:

Accepted Answer

The catalyst efficiency is low and it is failing

Answer

The catalyst is functioning efficiently

Answer

The upstream O2 sensor is faulty

Answer

The engine is running lean