How to Fix P1507 DTC Code on Cummins (The Expert Approach)

Car engines like the Cummins can often have problems due to various external factors. DTCs ( diagnostic Trouble Codes) help you identify these problems. Once identified, you can resolve it quite easily. 

Code P1507 on Cummins stands for “idle control under speed error.”  This error usually occurs when the PCM detects a sudden increase or decrease in the idle airspeed that exceeds the desired level. As such this can result in irregular idling when you drive your car.

In this article, we will cover everything you need to know regarding code P1507, including how to resolve it. Keep reading to learn the entire procedure.

How to Fix P1507 DTC Code on Cummins

What Does Code P1507 Mean On Cummins?

The P1507, as you might have already processed, is a Diagnosis Trouble Code (DTC). The IAC assembly is responsible for adjusting the engine idle speed while providing a functional dash. 

However, when the IAC is not able to adjust these levels and the idle airspeed is not within the desired levels, the PCM detects the problem. It then sens signals for the code P1507 to be stored in your engine. 

This DTC affects the vehicle’s ECM which is located at the powertrain of the engine. It will prevent the idling processes to run smoothly while your vehicle runs a very deteriorated performance. 

Each letter in this code can be further broken down to get more technical coverage. We have compiled the full breakdown below for you to glance at.

  • P = Powertrain, the system of components that propels your car forward.
  • 1= It refers to a generic manufacturing code
  • 5= It represents the engine idle and corresponding vehicle speed
  • 07= Specific Fault Index (In this case, it refers to the idle air control under speed error)

How Serious Is Code P1507 On Cummins?

The code can be said to be moderately serious at best. While it won’t affect your vehicle’s performance soon, you will notice adverse effects in the long run. 

The most obvious issue can be a decrease in the overall power supply in the vehicle. It can also cause irregular operations during idling. 

As such, you are advised to resolve it when the best time arrives without any delay. However, there is no need for any rush since the code will not cause any engine problems in near future. 

What Causes Code P1507 On Cummins?

Numerous factors could cause the P1507 DTC. Below, we have listed some of the most common reasons for the code:

  • The idle air control valve could be left exposed due to wire or connector damage.
  • The valve might be blocked or stuck
  • The entire module might have become faulty
  • There might be cases of short-circuits
  • The solenoid is damaged
  • Faulty PCM
  • Lose control module straps or knobs
  • The air inlet is plugged in the wrong way

How To Fix Code P1507 On Cummins?

Fixing IAC valve-related problems might be a little too technical for most people. However, if you do have enough experience, you can keep reading the general procedure and follow through. 

Otherwise, it is best that you stick to hiring a professional mechanic to patch it up. Of course, this will cost you some money depending on the mechanic’s labor and extra parts that might have been used. 

Step 1: Run A Diagnosis

The first step in this procedure is to run a manual diagnosis on your vehicle. You can use an OBD-II scanner to help you out with running diagnostics on the various systems and modules in the engine.  

You can also run a visual inspection over the numerous parts, LED lights, and wires to check their normal operations. 

Inspect the wires and their cases for signs of wear and tear. Additionally, look for loose pins, knobs, connectors, or terminals. Everything that is related to the idle air circuit valve should be checked. 

Step 2: Repair Circuit

Make use of an ohmmeter or voltmeter and connect it to the IAC. Activate the meter and record the corresponding voltage. Since the voltage will keep fluctuating, take three different readings and record the final average. 

Once the present voltage has been recorded, check with the manufacturer’s manual to find out what the standard voltage in the IAC should be. 

If the values match or are close enough, the wires are fine. You will not need to make any repairs. On the other hand, if there is a huge difference between the two, you will need to fix the entire wire system. 

Step 3: Fix The Connector

The connectors, or pins, can bend or loosen up. Make use of a hammer or a blunt tool to fix bent pins or connectors. If this is not possible, replace them entirely. 

If there are any blockages within the connectors, make the appropriate adjustments. 

Step 4: Run Final Tests

Once you have patched up all the auxiliary parts, you can check whether the code still keeps getting triggered. 

If the code flashes again after the repairs, understand that the entire IAC valve might be damaged. If such a case arises, you might be required to change the entire valve. 

Other Symptoms Of Getting Code P1507 On Cummins

There are several symptoms that can be associated with the triggering of the P0650. Some of the more common ones have been included in the list below. 

  • The “Check Engine” light keeps turning on
  • Inconsistent performance during idling
  • Sudden loss of power during driving

How Much Does It Cost To Fix Code P1507 On Cummins?

The typical amount of money that you will spend on fixing the problem will only go towards hiring a professional. 

If you hire a mechanic, expect to pay around 80 to 150 USD based on the price of labor from the shop where you are hiring the mechanic. 

Additional costs may include the price of parts that could have been used to replace old, worn-out ones inside the engine. 

If you fix the issue on your own, you will be required to pay for only the necessary parts needed for replacement.  This is typically around 10 to 30 USD.

Can You Drive Your Cummins With the Code P1507?

Yes, you can indeed drive your car even if the problem persists. However, the user experience of driving the car while the code is triggered is never the best.

The car is throttled down to low power mode, and even running the car on idle will be a challenge. As such, fix the problem as soon as possible and then drive your car as much as possible. 


If you are here at the end of this article, you should already have understood everything about the P1507 code. Hopefully, this article has been a lot of help to you in your endeavors. 

The P1507 code might not be the most dangerous. However, that doesn’t give you the excuse that you shouldn’t resolve it. 

If you want the best performance from your vehicle with no issues, we recommend that you patch it all up. Otherwise, it will be too late to complain later on.

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