Ford F150: Idle Air Control System- Failure

P0505 An OBDII Code that addresses the idle air control system within the Ford F150.  It’s a generic code, which means that it has the same meaning for the F150 as it would any other vehicle (F150 or not).

P0505:  Idle Air Control System:  Malfunction

P0505 usually occurs due to a stuck idle valve or clogged idle valve.  However, there are other possible causes.  Although, they aren’t as prevalent.

P0505 Ford F150


Índice de Contenido
  1. P0505 Symptoms:  Ford F150
  2. F150 P0505 Causes
    1. Valve for Idle Air Control
    2. Vacuum Leak
    3. Carbon Buildup
  3. Conclusion

P0505 Symptoms:  Ford F150

This particular trouble code lets you know that there is something wrong with the idle air control system, but that’s about it.  The symptoms may vary.

These are the top symptoms of P0505.

  • Engine service engine will soon be light
  • It is a rough idle
  • Stalling
  • Low idle speed 


F150 P0505 Causes

P0505 can usually be caused either by a vacuum leak or an issue with the idle control valve.  While replacing the idle air control valve seems like a good idea, it’s worth your time to check for a Vacuum leak first.

Ford F150 P0505 Diagnosis

Valve for Idle Air Control

The idle air control valve’s primary job is to regulate the idle speed of your engine.  The idle air control valve regulates the engine's idle speed by controlling the amount of air that is allowed in.

It is possible for the IAC to become stuck or dirty.  It may be necessary to replace it or clean it.  Here’s a great You Tube video Here are some tips on cleaning an idle valve.  

You may need to replace your idle air valve if you feel it is time. Very affordable.


Vacuum Leak

While the idle air control valve is often the cause of P0505, it’s a great idea to start diagnosing it by looking for a vacuum leak.  Examine the vacuum tubes near the IAC.  It may be necessary to replace them if they appear cracked or dry-rotted.

You can code your F150 by leaking around the throttle bodies and intake manifolds.  Here’s a great article from Popular Mechanics on How to locate a vacuum leak.


Carbon Buildup

Carbon buildup can occur around the IAC's inlet.  The problem can be fixed by inspecting the IAC area for carbon-blocking passages.

The throttle body can become too dirty to allow air to enter the engine.  This can cause P0505 to be thrown.  Often, when this is the case, you’ll feel the engine stall for a second before it recovers when slowing down.  

This happens because the engine can’t adjust to this problem fast enough.  This problem is usually solved by cleaning the area around the throttle blades.



It's possible to find P0505 within your F150.  Most of the time it’s a vacuum leak or the idle air control valve.  If you feel like there’s anything that you can add, please feel free to leave a comment below.

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