P0505 OBD II Trouble Code IAC (Idle Air Control) System Malfunction

Detailed information on troubleshooting and repairing a P0505 DTC code which refers to a malfunction of the IAC (Idle Air Control) system. Also includes links to relevant forum topics on the code.

Symptoms of P0505 OBD II Trouble Code

  • MIL (Malfunction Indicator Lamp) illumination
  • Engine stalls and may not idle unless throttle is depressed
  • Intermittently stalls when letting off the throttle
  • Engine may idle too high

Common Causes of P0505 OBD II Trouble Code

  • IAC motor connector is damaged (check connector and pins for damage, and moisture)
  • One or more IAC circuits open or shorted to ground
  • One or more IAC circuits are shorted to voltage
  • IAC has failed
  • PCM has failed