Quality and quantity sensor with redundant low quantity measurement

A fluid sensing system comprising:

• a target positioned at a target level;
• a first transducer configured to generate a first sound wave in a vertical direction and to detect a first echo of the first sound wave;
• a second transducer configured to generate a second sound wave in the vertical direction and to detect a second echo of the second sound wave;
• and
• an electronic processor configured to:
• produce a first signal to drive the first transducer to produce the first sound wave,
• receive a first indication of the first echo from the first transducer,
• determine a first level of the fluid based on the first indication,
• determine the first level of the fluid is less than or equal to the target level,
• produce, in response to determining the first level of the fluid is less than or equal to the target level, a second signal to drive the second transducer to produce the second sound wave,
• receive a second indication of the second echo from the second transducer, and
• determine a second level of the fluid based on the second indication.