A method of determining and displaying a fluid level of a fluid in a container using a probe positioned within the container, the probe having a plurality of ultrasonic sensors located within a barrel, each of the plurality of sensors being located at a different fluid level in the container, the method comprising: (a) sending an electrical pulse to a first sensor of the plurality of ultrasonic sensors; (b) receiving an electrical signal from the first sensor in response to the electrical pulse sent in step (a); (c) performing step (a) on each of the plurality of ultrasonic sensors in a first sequence; (d) repeating step (a) at a first frequency; (e) determining a status of the first sensor for each performance of step (a) at the first frequency based on at least one electrical signal from the first sensor received in step (b), the status being selected from the group of: dry status, wet status and, optionally, error status, the wet status indicating a presence of the fluid at the fluid level at which the first sensor is located, the dry status indicating an absence of the fluid at the fluid level at which the first sensor is located; (f) changing the status of the first sensor as determined in step (e) to a different status than was determined in an immediately preceding performance of step (e) only if at least one predetermined condition is met; (g) performing steps (e) and (f) on each of the plurality of ultrasonic sensors; (h) repeating step (g); and (i) displaying a visual indication of the status of each of the plurality of ultrasonic sensors as determined in steps (e) through (g), characterised in that the probe comprises: a multi conductor shielded cable comprising a two-layer outer shield and a plurality of conductors (181, 182, 183), each of the plurality of conductors (181, 182, 183) being individually insulated but not individually shielded; wherein each ultrasonic sensor of the plurality of ultrasonic sensors is electrically connected to a separate one of the plurality of conductors (181, 182, 183) and to a first layer of the outer shield for common signal return and wherein a second layer of the outer shield is used for grounding. (a) sending an electrical pulse to a first sensor of the plurality of ultrasonic sensors; (b) receiving an electrical signal from the first sensor in response to the electrical pulse sent in step (a); (c) performing step (a) on each of the plurality of ultrasonic sensors in a first sequence; (d) repeating step (a) at a first frequency; (e) determining a status of the first sensor for each performance of step (a) at the first frequency based on at least one electrical signal from the first sensor received in step (b), the status being selected from the group of: dry status, wet status and, optionally, error status, the wet status indicating a presence of the fluid at the fluid level at which the first sensor is located, the dry status indicating an absence of the fluid at the fluid level at which the first sensor is located; (f) changing the status of the first sensor as determined in step (e) to a different status than was determined in an immediately preceding performance of step (e) only if at least one predetermined condition is met; (g) performing steps (e) and (f) on each of the plurality of ultrasonic sensors; (h) repeating step (g); and (i) displaying a visual indication of the status of each of the plurality of ultrasonic sensors as determined in steps (e) through (g), a multi conductor shielded cable comprising a two-layer outer shield and a plurality of conductors (181, 182, 183), each of the plurality of conductors (181, 182, 183) being individually insulated but not individually shielded; wherein each ultrasonic sensor of the plurality of ultrasonic sensors is electrically connected to a separate one of the plurality of conductors (181, 182, 183) and to a first layer of the outer shield for common signal return and wherein a second layer of the outer shield is used for grounding.