When the current sensor fails, the following situations may occur:

1. No or wrong output signal: A faulty current sensor may not produce a correct output signal, or may have no output signal at all. This results in an inability to accurately measure or monitor current values.

2. Unstable output signal: A faulty current sensor may cause fluctuations or jitter in the output signal. This will lead to errors in accurate current measurements.

3. Incorrect current measurements: A faulty current sensor may provide incorrect current measurements. This may be caused by damaged components within the sensor or a failed calibration.

4. Short circuit or open circuit: A faulty current sensor may cause a short circuit or open circuit in the sensor's circuit. This will cause the current measurement system to not work properly.

5. Overload protection triggering: Some current sensor designs may include overload protection features. When a current sensor exceeds its rated measurement range, it may trigger a protection mechanism that stops outputting a signal.

When a current sensor fails, it may result in an inability to accurately measure the current, errors or erroneous measurement results, and may have an impact on the normal operation of the current measurement system. In the event of a failure, the sensor usually needs to be serviced or replaced to restore normal operation.