Principal business code for CA Form 3514

I get error message indicating I need to enter Business code (from Fed Sch C (form 1040) box B) on Line 18for CA Earned Income Tax Credit Form 3514

There is no Sch C in my return.  I am unable to find business code on K1 that I received from employer.

Have received K1 for many years and never had issue before. I can't find 3514 on prior year returns

The K1 has Partnership EIN.  Can I enter this as the SEIN on line 18 of Form instead?