As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LARGE PUDDLE OF OIL DISCOVERED UNDERNEATH ENGINE #2 DURING PREFLIGHT. GROUNDED - YES. PERFORMED INSPECTION FOR OIL LEAK ON #2 ENG. FOUND CAP ON OIL TANK OPEN. SECURED CAP AND CLEANED ESIDU FROM AREA. B737-9 AMM 71-71-00-200-801-F00. OIL QTY IS WITH IN LIMITS PER AMM 12-13-11-600-801. AIRCRAFT OK FOR SERVICE.