Service engine soon light is on

I plug in my OBD2 computer under the dash. I’m getting codes PO676 and PO683. I changed #6 glow plug and the relay for the glow plug. I reset the computer but the light came back on with PO676 code. Can you please help.

Sorry I don’t know those codes, but just for the record, that should have been a CEL (Check Engine Light) the Service Engine soon Light is is something different. ?:slight_smile: