An oxygen sensor is being tested with a digital multimeter using the MIN/MAX function. The readings are: minimum = 78 mV; maximum = 932 mV; average = 442 mV. Technician A says that the engine is operating normally. Technician B says that the oxygen sensor is skewed too rich. Which technician is correct?

Question

Quizplus · Accepted Answer

The oxygen sensor readings indicate a normal range of operation for a typical vehicle. The minimum value (78 mV) suggests the mixture is sometimes lean, and the maximum value (932 mV) indicates it can also be rich, which is normal as the engine adjusts the air-fuel mixture. The average value (442 mV) is close to the midpoint of the sensor's range, suggesting balanced operation. Therefore, Technician A is correct in saying the engine is operating normally.

An Oxygen Sensor Is Being Tested with a Digital Multimeter