Technician A says that poor fuel economy is usually due to an excessively lean air-fuel mixture. Technician B says that a rich air-fuel mixture can be caused by a defective oxygen sensor. Which technician is correct?

Question

Quizplus · Accepted Answer

Technician B is correct because a rich air-fuel mixture can indeed be caused by a defective oxygen sensor, which might incorrectly signal that the air-fuel mixture is too lean, prompting the engine to add more fuel than necessary. Technician A is incorrect because poor fuel economy is more often associated with a rich air-fuel mixture, which uses more fuel than needed, rather than a lean mixture.

Technician a Says That Poor Fuel Economy Is Usually Due