What was found
WHILE CHECKING APU OIL FROM FLT DK, - NOT ABLE TO CHECK - SHOWS UNKNOWN. GROUNDED - YES. BITE CHECK OF APU PER B737-800 FIM 49-60 TASK 801 SHOWS MSG 49-94304 OIL LEVEL SENSOR SHOWS CIRCUIT FAILURE. PULLED AND TAGGED 2 CB'S TO CHECK OIL LEVEL SENSOR ON APU. CHECKED SECURITY OF CANON PLUG AT OIL LEVEL SENSOR. RESET 2 C/B'S REMOVED TAGS - STILL SHOWS UNKNOWN ON QTY CHECK. R/R APU OIL LEVEL SENSOR PER B737-800 AMM 49-94-11-000/400-801. OPS TEST GOOD. NO LEAKS. ADDED OIL TO APU AS NECCESSARY.