Technical Definition:

Idle Air Control System

Trouble Code: P0505
Address: 0x0505
System: Powertrain
Subsystem: Vehicle Speed Control, Idle Controls, and Auxiliary Inputs
Technical Description:

Possible Causes:
  • IAC motor connector is damaged
  • 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

Possible Symptoms:
  • 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

Idle Control System Malfunction

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Faulty IACV-AAC valve
– IACV-AAC valve harness is open or shorted
– IACV-AAC valve circuit poor electrical connection

Specific Makes:

– Engine hard to start
– Rough or erratic idle speed

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