Identify a common symptom of a failing turbocharger.

A common symptom of a failing turbocharger is loss of power and excessive exhaust smoke. When a turbocharger is functioning correctly, it increases the efficiency and power output of an engine by forcing more air into the combustion chamber. If the turbocharger begins to fail, there is often a significant drop in the engine's power because it is unable to boost the intake air pressure effectively.

Excessive exhaust smoke can occur as a result of oil leaking into the combustion chamber, which is a common issue with failing turbochargers. This leakage can lead to a visible increase in smoke from the exhaust, indicating that the engine is burning oil along with the fuel. This combination of loss of power and increased smoke serves as a clear warning sign of turbocharger issues, alerting the mechanic to investigate further.

In contrast, other options such as increased fuel economy, improved engine sound, and lower engine temperatures are not indicative of turbocharger failure and can mislead one to believe the engine is running optimally when, in reality, significant mechanical issues may be present.