What are causes and Symptoms of P0505? | How to fix code P0505?

The 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 examines the symptoms and causes of the code P0505.

What Does the P0505 Code Mean?

Diagnostic trouble code (DTC) P0505 represents the “Malfunctioning of Idle Control System.” In general, P0505 means that the computer of your car’s engine is unable to control the idle speed. This results in a difference in the actual and the targeted idle speed due to the faults in the air transmission or your car.

p0505 code

In simple terms, you might state that the P0505 code will appear if your automobile experiences any problems with air intake or exhaust when it is in an idle position.

Working of Idle Control Valve

An 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 idling.

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.

Causes of Trouble code P0505

Code P0505 can be due to many different causes, but the intake manifold vacuum lean and faulty idle air control motor is the potential ones. The reason behind it 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.

Following are the major causes of code P0505:

  • Vacuum leak       
  • High carbon buildup inside the throttle body
  • PCM issues like software upgradation etc.       
  • The problem with IAC circuitry like damaged or loose wires
  • Out of calibration idle speed

Read More: Symptoms and Causes of bad PCM

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 and trouble code in ECM memory
  • Frequent high-engine idling
  • The lower or higher engine idle
  • The engine stalls when the car approaches to halt
  • Rough engine idle

Read More: Causes and Symptoms of P0506

How to diagnose the code P0505

  • Verify the code from PCM and clear it once scanned.
  • Take your car to a test drive and notice the engine idle.
  • Clarify the vacuum leak through a test.
  • Inspect the carbon buildup in the treadplate and IAC valve.
  • Remove the IAC to determine if the engine’s base idle is within specifications.
  • Inspect passages by removing and examining IAC.
  • There are some frequent traps to avoid while troubleshooting the P0505 code.
  • In the case of the IAC valve replacement, the IAC passages should be cleaned first.

Read More: Different types of Engines

Frequently Asked Questions

How serious is the code P0505?

  1. Code P0505 is due to the malfunction of the IAC. Therefore, as the IAC goes bad, the engine can idle too low or too high, and sometimes the engine can also stall once it goes too slow.
  2. In case of a vacuum leak, you may face rough engine idle and bad fuel economy.
  3. If the check engine light is on, your car may fail to pass the emission test.

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.

What repairs can fix the P0505 error code?

Follow the below-given steps to fix the P0505:

  • Check the IAC valve and replace it if needed.
  • Carefully clean the passages and throttle body.
  • Remove the excess carbon from the throttle body and IAC passages.
  • Repair gas leak.

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 your car even if the trouble code is on unless the engine stalls or stutters in a way that makes the car hard to drive.

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