Blower keeps running after cycle is complete. At beginning of heating season replaced thermostat batteries and ran good since. Six months later doing it again and new batteries didn't help. Cleaned flame sensor. Error code 8 red flashes. Igniter looks like it could be worn down or broke off in middle but seems to light fine. Why does blower not shut off?

What is the meaning of the 8 code? There should be a key to the code on the inside of the blower compartment door.