A fluid detection system comprises a liquid sensor, an air pump and an atmospheric pressure sensor encased within an air and water permeable casing defining an enclosed air space. The pressure sensor acquires pressure samples within the casing, the air pump expelling additional gas into the casing. In response to determining a flood-status or a non-flood-status state of the fluid detection system and comparing the samples, a failure of the fluid detection system or an immersion of the fluid detection system in fluid is determined. In some embodiments, failure is determined if a second sample is greater than a first sample in a non-flooded state, and in others immersion is determined if a second sample is greater than a first sample value and the determined state is flooded. In some examples, gas is expelled across a liquid detection surface and a third sample value is acquired.