Yes, a check engine light will cause your car to fail CA Smog Test. The protocol includes both emission control electronics and exhaust gas emissions. California and some other states are moving toward electronics only testing and dropping the emission portion of the test.

Since the light is on for a reason, you need to determine the problem. Even if you could clear it, it would likely reappear before you got to the Test station.

Check the archives for posts on how to determine OBD codes for your model/year.

Good luck.