What condition may indicate a vacuum leak in an engine?

A vacuum leak in an engine can lead to a variety of performance issues, and one of the most significant consequences is poor fuel economy. When there is a vacuum leak, unmetered air enters the engine along with the regular amount of fuel, leading to a lean air-fuel mixture. This lean mixture can cause the engine to run inefficiently, resulting in an increase in fuel consumption as the engine struggles to maintain performance. Over time, drivers may notice that they need to refuel more frequently as a direct result of this inefficiency.

In contrast, stable engine RPM typically indicates that the engine is running smoothly and is properly calibrated, which would not be expected if there were a vacuum leak. High engine temperature is often a symptom of cooling issues or engine overload rather than a direct result of a vacuum leak. Increased oil pressure is generally related to oil system problems rather than air intake issues. Therefore, poor fuel economy is the most direct indicator that a vacuum leak may be affecting engine performance.