Advanced Diagnostics

Advanced Diagnostics - 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.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
The MCM receives a failure information which is related to the auto idle stop prohibition from the PCM for at least 2 seconds.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the MCM memory. If the malfunction returns in the next (second) drive cycle, a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.