Recently, Duncan Aviation airframe technicians worked a Falcon 900EX that repeatedly tripped the fuel magnetic indicator with an 813 code.
After researching old documentation, we discovered that while depressing the warning panel light test switch, the fuel detector thermistors (23EJ and 29EJ) are heated to simulate an empty fuel tank. Depending on the temperature, this test can take up to, but not more than 5 seconds.
So in order to avoid an untimely or false tripping of code 813 and red fuel minelco, hold the warning light test switch until the “central tank” light illuminates.
Falcon 900 and Keeping your Cool