Acura TL 0505: Idle air control system-malfunction

P0505 This OBDII code deals with the idle control system of the Acura TL.  It’s a generic code, which means that it has the same meaning for the TL as it would any other vehicle (TL or not).

P0505:  Idle Air Control System:  Malfunction

P0505 usually occurs due to a stuck idle valve, a blocked idle valve control valve or a leak.  Other causes can also be involved.  Although, they aren’t as prevalent.

P0505 Acura TL


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

P0505 Symptoms:  Acura TL

This particular trouble code lets you know that there is something wrong with the idle air control system, but that’s about it.  These symptoms could be different.

Below are some symptoms that P0505 is most commonly seen:

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


Causes TL P0505

P0505 will usually indicate a vacuum leakage or a problem in the idle air valve.  While replacing the idle air control valve seems like a good idea, it’s worth your time to check for a Leakage of vacuum first.

Acura TL 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 How to clean an idle air control 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.

Leakages around the throttle body, intake and manifold leaks can all code your TL.  Here’s a great article from Popular Mechanics on How to spot a vacuum leak.


Carbon Buildup

It is possible for carbon to build up around the IAC inlet.  The problem can be fixed by inspecting the IAC area for carbon-blockage passages.

It can cause the intake of air to be reduced if the throttle body becomes too dirty.  You can even throw P0505.  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.  It is possible to fix the problem by cleaning it from around the throttle blades.



You will be able to diagnose P05055 in your TL.  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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