For what reason is carbon monoxide (CO) much less of an emissions problem in diesel engines than in gasoline-fueled engines?

Question

Quizplus · Accepted Answer

Diesel engines typically operate with a leaner fuel/air mixture compared to gasoline engines. This means they use more air and less fuel, which is farther from the stoichiometric ratio where the optimal fuel and air mix would completely burn all components. Since carbon monoxide (CO) is primarily produced when there is insufficient oxygen to convert all the carbon in the fuel to carbon dioxide (CO2), the excess air in diesel engines helps ensure more complete combustion, thus reducing CO emissions.

For What Reason Is Carbon Monoxide (CO) Much Less of an Emissions