P0506 Code: Idle Air Control System RPM Lower Than Expected

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The engine idle control system is one of the most vital elements of your vehicle. The vehicle idle system helps to maintain the working of your car in its idle state and keeps it safe from blocking or stalling, most importantly when the high-power consuming components (AC, radiator) of your car are running. Learn the P0506 code meaning and causes.

Due to the fault in your car’s idle control system, many OBD-II trouble codes may trigger. The code P0506 is triggered when your vehicle’s idle system doesn’t work properly and the idle RPM becomes lower than the specified limit. This mainly explains the P0506 code meaning, causes, symptoms, and how to fix it.

P0506 Code Definition

The P0506 code stands for “Idle Air Control System RPM Lower than Expected.”

What Does the P0506 Code Mean?

The code P0506 indicates that your PCM has monitored that the idle RPM is lower than the specified limit.

The P0506 error code is most commonly triggered in vehicles that contain an IAC valve or Electronic Throttle Control (ETC). The IAC valve plays a vital role in regulating the idle RPM of your car. It adjusts some air that evades the throttle blade of the car.

Alternatively, the Throttle cable and IAC valve are not present in the vehicles with Electronic Throttle Control (ETC). Therefore, these vehicles depend on the electronic motor to regulate the idle RPM and control the throttle.

The engine’s idle RPM should ideally be maintained between 750 RPM and 1000 RPM while the vehicle is idling. When the idle speed becomes lower than 750 RPM, the PCM of your car triggers the DTC P0506.

However, there are multiple causes of the P0506 code. Therefore, you must properly find and fix the cause on time before the RPM of the engine at an idle state matches its normal SPM. To fix this code properly, you must drive your vehicle to a mechanic and ask him to fix it.  

Causes of Code P0506

Several primary problems may trigger the diagnostic trouble code P0506. Having a clear understanding of these potential problems may drastically reduce the amount of time needed for diagnostics and repairs, allowing you to get your car back on the road quickly.

The following are the common causes of the P0506 code:

  • The damaged Idle Air Control (IAC) valve
  • An issue with the PCM
  • Faulty Positive Crankcase Ventilation (PCV) valve
  • Fault in the Electronic Throttle Control (ETC) system
  • Damaged wires or bad circuit connections
  • The clogged intake and exhaust valves
  • Defective or contaminated throttle body
  • The issue with the power steering pressure switch
  • Vacuum leaks

Symptoms of Code P0506

An illuminated check engine light is one of the most common symptoms of the P0506 code. However, the P0506 code may also trigger the following symptoms:

  • Rough engine idle
  • Engine stalling as your vehicle comes to a stop
  • Illuminated check engine light
  • Low engine idle speed
  • Poor engine performance 
  • Rough Idle

How to diagnose the P0506 code?

Follow the below-given steps to diagnose the P0506:

  • Scan all the trouble codes from the PCM of the car through the OBD-II scanner.
  • Examine the freeze frame data to analyze the status of the engine at the setting time of the trouble code. Clear the codes and perform a test drive. If the P0506 code returns, perform further inspection. 
  • Check the damaged wiring between your car’s engine’s air filter housing and throttle body.
  • Check if the air filter needs replacement. If yes, replace it.   
  • Examine your car’s engine throttle body and see if you find any evidence of high-carbon fouling. Now, clean the fouling with the proper solvent and a nylon brush.
  • Properly examine the idle air control valve of your vehicle for damage. 
  • Examine the electrical harness connected to the idle control system.
  • Test the serious vacuum leaks. These leaks can be tested using different methods, but the smoke machine is one of the most effective tests for this purpose.
  • Inspect the PCV valve for a damage. 
  • Check the performance of your PCM using a scan tool.
  • Clear the codes and perform a test drive.

P0506 Code Diagnostic Mistakes

  • Ignoring basic checks 
  • Not inspecting the throttle body for a fault
  • Ignoring the inspection of the IAC system
  • Overlooking vacuum leaks
  • Overlooking intake and exhaust restrictions
  • Failing to update the needed PCM software
  • Overlooking other related codes stored in the PCM memory 
  • Installing the parts without testing them

What repairs can fix the P0506 code?

To fix the P0506 code, you need to perform one or more of the following repairs:

  • Clear the PCM memory and perform a test drive
  • Replace the faulty IAC valve
  • Repair the possible vacuum leaks
  • Replace the faulty idle air control motor
  • Clean the dirty throttle body
  • Clean the clogged intake or exhaust system
  • Replace the faulty throttle body
  • Replace the bad PCV valve
  • Repair the issues related to PCM

Repair Cost of P0506 Code

The repair cost of P0506 varies according to the nature of the damage. For example, the cost of throttle body cleaning is from $230 to $310. However, the replacement cost of a bad IAC valve is from $140 to $510.

FAQ Section

What is meant by Trouble code P0506?

P0506 means that your car is not idling efficiently, and the idle speed is quite lower than the expected RPM. The latest vehicles have ETC to calculate the idle speed of the engine. As you see this trouble code, it means you have a faulty electronic throttle control (ECT).

How serious is the Code P0506?

The code P0506 is typically considered highly serious because it can impact an engine’s capacity to run as designed. The engine of a vehicle is intended to idle at a certain RPM range without faltering or stalling. This fault may cause bogus functional parameters. In an intense situation, the car may stall while going to stop. Hence it is a little risky to drive the car while your car is showing P0506.

Is it safe to drive with the P0506 code?

Sometimes, due to P0506, your car power may be lost while driving, and this loss of power may cause some crucial driving conditions. That is why code P0506 is referred to as a serious one. It is recommended to diagnose and fix this code as early as possible.

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