P0505 Code: Meaning, Symptoms, Causes, And Fixes

The powertrain control module (PCM) is a major part of the vehicle. It takes data from different engine sensors and uses it to regulate the spark timing and air-fuel mixture supply. As your idle control system goes bad, the PCM triggers the trouble code P0505. In other words, if your car is facing some issues in the air taking in an idle position, then you will get the code P0505. This article mainly explains the P0505 code meaning, causes, and symptoms.

P0505 Code Definition

The P0505 code stands for “Malfunctioning of Idle Control System.” 

What Does the P0505 Code Mean?

The P0505 code represents that your vehicle’s PCM detects an issue with the idle control system. The idle is too low or goes too high.

p0505 code

In the case of old vehicle models, the Idle Air Control (IAC) valve is located near the throttle body of your car. By monitoring the quantity of air entering the throat of the throttle plate, the IAC’s purpose is to maintain the idle speed. But for the proper functionality, an idle-state engine still needs some air.

At that stage, the PCM sends the instructions to the idle control system to open the bypass air passageway. 

Idle Air Control Valve

The Idle control system of the car controls the air quantity that must be supplied to the idling engine. That is done with the adjustment in the size of the opening of the bypass airway. Hence the idle speed can be controlled with the increase or decrease of the airflow.

The PCM of your car tracks down the existing load on the idle system. So, the idle control system of the car regulates the airflow to supply the needed air to the engine at idle.

Like all other car parts, the idle control system of the car also gets damaged or can wear out with time. A bad Idle control system interrupts the idle speed of the engine, and hence the PCM of the car shows trouble code P0505.

Causes of P0505 Code

Code P0505 can be due to many different causes, but the intake manifold vacuum leak and faulty idle air control motor are the most common causes. The reason behind this is that the proper functionality of the air control motor depends on the vacuum, and a leak in a vacuum can cause a bad Idle air control motor.

The following are the major causes of code P0505:

  • Vacuum leaks       
  • Carbon buildup inside the throttle body
  • PCM issues like software need to be updated etc.       
  • The problem with IAC circuitry like damaged or loose wires
  • Bad PCV valve
  • Damaged IAC motor connector
  • Bad IAC valve 
  • Idle speed out of calibration

Symptoms of Code P0505 

When your vehicle experiences a problem with your IAC valve, it triggers the P0505. When your car experiences code P0505, it gives one of the below-given symptoms to alert the driver:

  • Illuminated check engine light
  • Frequent high-engine idling
  • Rough idle
  • Your engine may die when the engine coming to a stop. 
  • Rough engine idle
  • Reduced engine power

Read More: Causes and Symptoms of P0506

How to diagnose the P0505 Code

Follow the following steps to diagnose the P0505 code:

  • Verify the existence of the P0505 code in the PCM memory by using a scan tool and clear it once scanned.
  • Take your car to a test drive and notice the engine idle.
  • Perform a thorough test to find the possible vacuum leaks.
  • Inspect the throttle body for carbon buildup.
  • Remove the IAC to determine if the engine’s base idle is within specifications.
  • Inspect passages by removing and examining the IAC.
  • Properly examine the PCM for a fault.
  • In the case of the IAC valve replacement, the IAC passages should be cleaned first.

Read More: Different types of Engines

How serious is the P0505 engine code? 

The proper airflow to the engine is vital to achieve optimal engine performance. When encountering a P0505 engine code or observing associated symptoms, it is recommended to instantly contact a professional mechanic for proper inspection.

When your engine doesn’t receive a sufficient supply of airflow, it needs to work harder or stall. In the short term, this may result in unexpected breakdowns, leaving you stranded. In the long term, it can cause premature wear and tear on engine components. Therefore, it is recommended to fix the P0505 code promptly to prevent yourself from expensive repairs.

What repairs can fix the P0505 Code?

You need to replace or repair one or more of the below-given parts to fix the P0505 code:

  • Replace the faulty IAC valve
  • Carefully clean the passages and throttle body
  • Remove the excess carbon from the throttle body and IAC passages.
  • Repair the vacuum leaks
  • Repair or replace the bad throttle body
  • Replace the faulty PCV valve

How to Prevent the P0505 Code?

Follow the below-given control measures to prevent the P0505 trouble code from triggering:

  • Address any engine issues on time 
  • Regular maintenance 
  • Ensure regular inspection of your intake system 
  • Ensure proper cleaning of the air filters
  • Ensure proper cleaning of the throttle body
  • Ensure regular maintenance of the idle control system
  • Drive safely 

How much does it cost to fix the P0505 Code?

The fixing cost of DTC P0505 depends on your vehicle mode, your living area, and the relevant faulty part. Following are the costs to repair P0505 according to the relevant faulty part:

  • IAC Valve replacement: $110 to $530
  • PCV Valve replacement: $180 to $240
  • Throttle Body cleaning: $80 to $270

Frequently Asked Questions

Can I drive my car with a P0505 trouble code?

You shouldn’t drive your car when your car shows the P0505 trouble code, but you can drive for a short period. Driving with this code for a long distance may lead to the damage of costly engine parts. Therefore, you should fix this code promptly.

What happens when idle air control fails?

When the idle air control valve fails, it inhibits the flow of air through the engine. When the car can’t receive air, it leads to engine stalling. The severity of this symptom can range from occasional stalling at first, to stalling immediately after ignition.

Is it safe to drive with a P0505 code?

Yes, it is usually safe to drive a vehicle with the P0505, but it may lead to certain problems, depending on the extent of the issue. If this code occurs due to high idle speed, it may make it challenging to decelerate or bring the vehicle to a halt. Conversely, if the idle speed is excessively low, your engine may stall at idle.

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