DTC P1C17: Idle Control System Rpm Higher Than Expected (HPCM): Diagnosis

WARNING: This page is about a different car, the 2015 Subaru XV Crosstrek. However, it is still accessible from the selected car via links, so may be relevant.

Detected when two consecutive driving cycles with fault occur. (Single engine startup is counted as one drive cycle.)
GENERAL DESCRIPTION < Ref. to DTC P1C17 IDLE CONTROL SYSTEM RPM HIGHER THAN EXPECTED (HPCM) , Diagnostic Trouble Code (DTC) Detecting Criteria.>