What effect can a faulty PCV system have on engine performance?

A faulty Positive Crankcase Ventilation (PCV) system can lead to increased emissions. The PCV system is designed to recirculate gases that escape from the combustion chambers back into the intake manifold, where they can be burned again instead of being released into the atmosphere. If the system is not functioning properly, it may allow excessive amounts of these unburned hydrocarbons and other pollutants to escape, contributing to higher levels of emissions.

When the system is clogged or malfunctioning, it can also lead to incomplete combustion, which results in more pollutants being produced and expelled through the exhaust system. This not only affects the environment but can also lead to failure during emissions testing in some jurisdictions. Therefore, the most direct consequence of a faulty PCV system is an increase in emissions, validating the selected answer.