DTC P15C4 (118): Auto Idle Stop System Malfunction: General Description

There are several system or units (for example the A/C system) where if they detect a malfunction, can over-ride the auto idle stop and keep the engine running.

If one of these systems or units over-rides the auto idle stop, the corresponding warning indicator comes on.

Not every unit or system that can over-ride the auto idle stop has its own indicator. In these cases, the system or unit sends signal to the powertrain control module (PCM), which sends a signal to the motor control module (MCM) to turn on the IMA system indicator and stores a DTC.