Can modifications to a vehicle’s emissions system impact emissions testing results?

Unauthorized modifications to a vehicle's emissions system can indeed lead to higher emissions and increase the likelihood of failing emissions testing. When a vehicle's emissions system is altered or tampered with—whether it involves removing components, replacing parts with non-compliant alternatives, or otherwise bypassing emissions controls—it can significantly compromise the vehicle's ability to control pollutants.

Emissions testing is designed to measure a vehicle's output of harmful substances. When modifications are made without following regulatory guidelines, the vehicle may emit more pollutants than allowed by law, leading to a failure during the testing process. This is particularly relevant in states like Pennsylvania, where strict emissions regulations exist to protect air quality.

In contrast, the other choices imply that modifications either have no effect on emissions or that only specific modifications matter, which does not accurately represent how emissions systems function. Aesthetic modifications, for instance, do not have any bearing on emissions tests, and stating that all modifications are permissible undermines the purpose of regulations aimed at reducing pollution.