Fix P0508 Obd2 Code: Idle Air Control System Circuit Low

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How To Fix P0508 Obd2 Code?
Table of Contents

A low idle air control system circuit is indicated by the appearance of the code P0508 and the subsequent storage of the code in the onboard computer.

P0508 Meaning:

P0508 Meaning:

This number indicates that the powertrain control module has detected an irregularity in the engine’s idle rotational speed. PCM will attempt to adjust the RPM to determine whether the engine is idling excessively high or low. It will be able to save the code if they are not able to.

OBD-II Code P0508: Symptoms, Causes & Diagnose


A P0508 code indicates that the engine idle RPM is either too low or too high. When the engine is moving at low speeds and the accelerator is not really pushed, it may stall. 

In addition, when the throttle is released, the engine may stall. As a result, a malfunction indicator light is likely to be activated.


A few of the most prevalent reasons for the P0508 error code include the following:

  • The motor harness for the IAC, or idle air control, may be shorted or open.
  • Due to the motor circuit, the IAC might also have a poor electrical connection.
  • A problem with the IAC may have to be blamed.
  • Throttle body bores that need to be cleaned out.

Methods of Diagnosis:

Diagnose the P0508 error code by having a technician attach an OBD-II scanner to the car’s onboard computer. They will next check to see if any codes have been saved and reset them. 

After that, they’ll test the car to see if the error code is appearing again. If the P0508 Obd2 Code error number appears again, they will investigate possible reasons like the IAC.


  • The tools that make up the toolbox.


It’s always a good idea to check for technical service bulletins (TSBs) for your specific car. Diagnostic time and costs might be reduced if your problem is already well-documented and has a known cure from the manufacturer. 

A diagnostic scanner, digital voltage/ohmmeter (DVOM), and reliable vehicle information source are all necessary tools for diagnosing code P0508 (All Data DIY will do). 

  • First, you have to check and repair any broken, corroded, or burned wiring and electrical contacts in the IAC system. 
  • If the engine RPM level is unmanageable, you would also examine the engine for any vacuum leaks. Repair vacuum leaks and rechecks and verify the system if you discover any. 
  • After that, you would hook up the scanner to the car’s diagnostic port, pull up all the saved codes, and freeze frame data on the drive back to my house. 
  • As a precaution, you would want to have a copy of this code handy in the event that it becomes unstable. Now you have to reset the car by erasing the codes and taking it for a spin.
  • To begin with, if there are any additional IAC-related codes recorded, you’ll need to investigate and correct them first. For the vehicle and problem in question, examine all service bulletins and safety recalls. 
  • Before calling the issue solved, drive the vehicle generally after any repairs have been made and enable the PCM to enter ready mode. You use a work cloth and my fingers to manage the engine RPM at idle while the IAC valve is unbolted from the engine to test the IAC system. 
  • After removing the IAC valve, you can tell whether the IAC system is malfunctioning if you can maintain a high idle speed. At idle, if you can’t keep an eye on the RPM, you are going to assume there’s a significant vacuum leak. 
  • Intake manifold gasket leakage, PCV valves/hoses, vacuum booster, check valve or pipes, EGR valve jammed open, EGR gasket leakage or PCV valve/hoses are all possible causes of large engine vacuum leaks. 
  • Look into your vehicle’s owner’s manual for instructions on using the DVOM to test the IAC motor. If the IAC motor/valve does not meet the manufacturer’s standards, get a new one and install it.

When diagnosing P0508 Obd2 Code, there is a typical error that must be avoided:

One typical blunder when troubleshooting the P0508 error code is to assume that the problem is with the IAC components right away. Cleaning the throttle body bore has a chance to help solve the issue in certain circumstances.

How to resolve error code P0508:

How to resolve error code P0508:

  • Repairs and techniques for determining a P0508 code are outlined below.
  • To begin, they’ll see whether the P0508 error code was accidentally set.
  • The throttle body should be checked and cleaned if the code is authentic, then the code should be rechecked.
  • Using the IAC, they’ll make sure all electrical connections are operating correctly, and if they need to be replaced or repaired, they will do so.
  • They may have to replace the IAC in certain circumstances.
  • Changing the PCM is a possibility, although it is highly unusual.

Tips for avoiding future occurrences of the P0508 obd2 error:

In most cases, the driver is alerted to the presence of the P0508 error code as soon as it occurs. Even if the automobile can still be driven, the idle will need to be corrected because of the many problems it is experiencing. 

You should not postpone having this issue resolved by a knowledgeable and qualified specialist. Maintaining the vehicle’s excellent operating condition requires that any development issues be addressed as soon as they are identified and addressed.

Do you know what the P0508 error code’s severity is?

Having the P0508 code indicates that the engine’s idle RPM is too low, which is something that no one wants to encounter when driving in their vehicle. It has previously been written above that the engine may stall at low speeds and when the accelerator is not engaged. 

This will probably occur. If you have this trouble while driving, it might be dangerous and result in tragic results. This code must be resolved as soon as possible to keep the vehicle operating at its typical level of performance. 

It is conceivable that the car may develop further problems if this and other codes are not handled.