A control apparatus for detecting a variation of a fluid level in a tank is disclosed. The control apparatus includes an Electronic Control Unit connected to the fluid level sensor. The ECU is configured to monitor a signal value representative of a fluid level in the tank; filter the fluid level signal value using a first filter to obtain a first filtered signal and using a second filter to obtain a second filtered signal, the first filter having a time constant (τ1) lower than a time constant (τ2) of the second filter; calculate an integral value of a difference between the first filtered signal and the second filtered signal; and generate a signal representative of the detection of an increase in the fluid level in the tank when the integral value is greater than a predefined threshold.