Hello and welcome to Just Answer,
The code you are seeing flash is the change oil code. The code is stricking based off of the hour meter. The code will come on at exactly 50 hours and stay on for 2 hours and then go out. It will repeat this every 50 hours. If the oil was changed prior to the specified 50 hour interval then just run the mower until it lights comes on again at the 100 hour mark and then change the oil again. The light cannot be rest.