Regarding catalytic converters, which technician is correct about their performance impact?

A defective catalytic converter can indeed lead to an increase in emissions while not having an immediately noticeable impact on engine performance. Catalytic converters are designed to reduce harmful emissions without significantly affecting the efficiency of the engine. However, different failure modes can lead to situations where the converter is impaired in its emission-reducing capabilities.

For instance, if the catalyst material inside the converter becomes damaged or contaminated, the engine may still run relatively normally in terms of power and drivability, yet the vehicle may produce higher levels of harmful pollutants due to incomplete combustion or unconverted exhaust gases. This scenario allows for a situation where emissions are elevated without a corresponding decrease in engine power, aligning with what Tech B states.

Additionally, the way an engine performs can also depend on many factors, including the overall condition and tuning of the engine itself. In some cases, even with a partially dysfunctional catalytic converter, an engine might still run efficiently enough to mask any performance decline until more severe damage occurs, making Tech B's assertion a valid point regarding the nuanced relationships between emissions and performance.

This understanding emphasizes that while catalytic converters play a crucial role in controlling emissions, their defects don’t always result in detectable drops in performance, which is why Tech B's statement holds true.