Customer explained that furnace was flashing a 13 error code. This error was a lockout code. Fired furnace and it ran consistently for about 15 minutes and shut off. Found high temperature safety to be open. Diagnosed a failed safety. It was opening prematurely before it’s rated temperature. Replaced failed part tested operation. Adjusted gas pressure down to rated specification. Blower wheel is in need of cleaning and we do recommend to ensure proper airflow and Efficiency. I do strongly encourage and full furnace tune up to ensure there are no other issues with system. Furnace operating normal at this time.