When is a catalytic converter considered to be functioning properly?

A catalytic converter is considered to be functioning properly when the back of the converter is at least 100 degrees or 5% hotter than the front. This temperature differential indicates that the converter is effectively processing exhaust gases. The heat generation occurs because the catalytic converter facilitates chemical reactions that reduce harmful emissions, and as these reactions take place, they generate heat.

If the back of the converter is significantly hotter than the front, it demonstrates that the catalytic materials within the converter are actively converting pollutants like hydrocarbons, carbon monoxide, and nitrogen oxides into less harmful substances. This temperature difference is a key indicator of the converter's operational efficiency, as it reflects the converter's ability to perform its intended function in the emission control system of the vehicle.

Other options suggest conditions that are not directly associated with the proper function of a catalytic converter. For instance, engine efficiency is complex and involves multiple components, while the replacement schedule may vary based on usage and vehicle specifications. Temperature readings are a more accurate and immediate indication of catalytic converter performance.