As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(LOG 5212870) AFTER APU START GOT BLUE MAINT LIGHT W/ODO SMELL THROUGH PACKS USING APU AIR. FOUND BOTH HYDRAULIC RESERVOIR OVERSERVICED. DRAINED EXCESS FLUID. REMOVED AND REPLACED COALESCER BAGS PER B737 AMM 21-51. NO OIL CONTAMINATION. RAN PACKS USING APU AND ENGINE AIR. NO ABNORMAL ORDER DETECTED.