2006 HHR,77,000 bought used,getting code P0013 Acuator Solenoid. Cost to fix? on 2006 Chevrolet HHR

DTC P0013 Exhaust Camshaft Position (CMP) Acuator Solenoid Control Circuit. 77,000 miles and t/c light keeps coming on but will go off in time. But continues to come back on.

Asked by for the 2006 Chevrolet HHR
cmp sensor issue need to be diag as to a circuit issue or sensor issue or mechanical issue