DTC P0505: IAC System Malfunction: Condition
WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0505 is set when Powertrain Control Module (PCM) cannot maintain target idle speed. Possible causes are:
- Idle Air Control (IAC) valve malfunction.
- Plugged air cleaner element.
- Plugged air intake passage.
- A/C relay control circuit malfunction.
- Generator control circuit malfunction.
- Low engine compression.
- Excessive engine blow-by.
- PCM malfunction.