A malfunctioning mass air flow sensor can lead to?

The correct response highlights that a malfunctioning mass air flow (MAF) sensor can lead to excessive fuel consumption. The MAF sensor measures the amount of air entering the engine, which is crucial for calculating the appropriate amount of fuel to inject for optimal combustion. If the sensor is faulty, it may provide incorrect readings, leading to an improper air-fuel mixture.

When the engine receives too much fuel (rich mixture) because of inaccurate data from the MAF sensor, it can cause excessive fuel consumption as the system tries to compensate for the perceived air volume. A rich mixture not only wastes fuel but can also lead to incomplete combustion, resulting in higher exhaust emissions and potential issues in engine performance.

The other options do not align with the impact of a malfunctioning MAF sensor. Improved throttle response would typically occur with proper functioning of the sensor, as it provides the necessary information for the engine control unit to adjust fuel delivery effectively. Reduced emissions usually result from efficient fuel combustion, which can be compromised by a faulty MAF sensor. Higher engine temperatures might occur due to other issues but are not a direct result of MAF sensor malfunctions, as the impact on fuel mixture and combustion efficiency would be more significant.