Abstract: This invention relates to a method of detecting the presence of a conductive fluid such as water in a chamber such as the oil pan of an internal combustion engine and apparatus for carrying out the method. A resilient flexible sensor probe is mounted in the oil drain and electrically connected to an alarm which is activated by current flow. The sensor probe has an outer electrode member with a portion formed of a helical coil through which an insulated wire runs to form an inner electrode member. The inner electrode member is connected to the alarm, while the outer electrode member is grounded to the engine. The sensor probe bends to a position where its inner end portion depends into contact with the bottom of the oil pan. The inner electrode member ends at a bare tip which is surrounded by an insulative sleeve which prevents direct contact with the bottom of the oil pan. The outer electrode member ends at a bare wire portion which is spaced a short distance from the tip of the inner electrode member.