P226C Code on 6.7 Cummins-Causes, Symptoms, and Solutions

There are a wide variety of problems that engine codes can indicate. That being said, if your 6.7 Cummins diesel engine is displaying the P226C code, you need to take action.

But what does the P226C code 6.7 Cummins engine mean?

P226C stands for “turbocharger boost control slow response.” This means there is a time delay between the action and its execution on the turbocharger. The code is triggered by either a faulty turbo actuator or the turbocharger itself. Rarely, an ECM fault or damaged wiring between the turbo and the ECM can be responsible for the problem. 

Next up, we will reveal the symptoms, causes, and solutions for this error code. Along with that, the severity of the error code will be outlined.

P226C Code on 6.7 Cummins: Causes, Symptoms, and Solutions

The error code indicates the turbocharger is not responding on time. That means, most likely, either the turbocharger itself or the actuator is not functioning like it is supposed to.

Other than the check engine light and the error code P226C, there would be other signs that tell you your turbo is having problems.




The turbocharger actuator is defective causing P226C code 6.7 CumminsThe check engine light is illuminated; the delay between accelerating and experiencing the torque rush, decreased engine performance.Replace the actuator
Turbocharger is defectiveReplace the turbocharger
The link between the turbo and the ECM is broken.Repair or replace the damaged wire
The ECM is defectiveReplace the ECU

How to Solve P226C Code on 6.7 Cummins?

Before we talk about the solution, let’s understand how it occurs in a little context.

The turbocharger adjusts its output by moving the position of the impeller nozzle. The ECM commands the actuator to the desired position. The turbo sensor detects the actual position and reports it to the ECM as feedback.

If the position feedback sent to the module differs from the commanded position sent to the VGT by more than a predetermined amount, the device rationality diagnostics will fail. It is inevitable that the engine’s performance will suffer if the turbo is not properly actuated.

Reason One: Turbocharger Actuator is Defective

The actuator is the part that executes commands from the ECM and controls the boost. So, in the case of a slow response, a faulty actuator will likely be the main culprit.


It is important to test your actuator to determine if that is the problem.

Right beside the turbocharger, the actuator is located behind the front passenger wheel.

  • It will be necessary to drain the coolant from your vehicle’s system and remove the front passenger wheel in order to access the actuator. 
  • The actuator can be removed by first removing the electrical connection, then unscrewing the bolts.  
  • Connecting the actuator to the turbo’s harness would be the simplest way to test it. Have someone else turn on the ignition. 
  • Once the actuator is turned on, the gear should move to the left. Upon turning it off, the gear should return to its original position. In the event that this does not occur or the actuator makes a buzzing sound while moving, there is a problem. 


Replace the actuator if it has gone bad. It would be best to test the condition of the new actuator before putting it in. Here is a video that may be helpful.

Reason Two: Turbocharger Is Defective

The turbocharger is composed of different components. You will have to check each component one by one to detect any problems.

  • Compressor Wheel: Get needle nose pliers and hold the center nut of the compressor wheel. Move it in and out then from side to side and see if it works. 

If you feel it’s movable and the wheel is rubbing up against the side of the turbo body, that’s a problem. Also, there should not be excessive oil on the blades of the compressor wheels.

  • The Wastegate:  You will need a vacuum gauge for this. Connect the vacuum gauge at the end of the wastegate. As you start vacuuming, the wastegate should move.

Upon disconnecting the vacuum, the diaphragm should move back to its previous position.

For the next parts, you will need to take the turbo system out of your engine.

  • The Diverter Valve: The diverter valve looks like a black plastic box that is screwed to the turbo. Detach the valve by taking out the screws. Look for any damage on the inner part of the valve. 
  • The Intake Hoses: Make sure that all the intake hoses are tightened and secured. 
  • The Turbine: Check all the fan blades of the turbine on both sides. See if they are damaged. Also, check if the blades spin properly. If they do not make noises while spinning, it’s not good.


The components of the turbo are not repairable. So, if any of the components are damaged, you will have to replace the whole thing.

This could be a lengthy process, so this video may help you.

Reason Three: The Connection Between the Turbo  & ECM Is Damaged

The connection between the turbocharger and the ECM must be checked if the turbocharger and actuator are working fine. A P226C code indicates that the ECM has detected a slow response from the turbo. So, it is likely that the connection between the turbo and the ECM is defective, even if the turbo is fine.

To check the functionality of the connection, disconnect the wire from the ECM and check for continuity with a multimeter. If that checks out, the wiring is fine.


If the problem is actually with the ECM wiring, then you must replace the faulty wire with a new one. Since this could be confusing or hard, it’s recommended to get professional help. You can expect to spend around $200 at most for a professional consultation.

Reason Four: The ECM Is Defective

If everything else fails, the only problem left is a faulty ECM. ECMs detect issues and store them in their memory, so if everything else is fine, it’s probably the ECM.

You will probably encounter many error codes in this situation. As a matter of fact, this needs to be addressed as soon as possible as well.

Testing an ECM requires a great deal of expertise and knowledge on the part of the tester. It would be better to call a mechanic if you suspect that.


There are practically no ways to repair a faulty ECM. So, replacing your ECM is a must if it malfunctions.

OEM ECUs can cost you up to 3000 dollars, not including labor, which can be another 500-1000 dollars. Comparatively, aftermarket ECUs cost around 500-800 dollars.

How Serious Is the P226C Code on 6.7 Cummins?

The P226C code is not that serious, as you will be able to drive around. But this is also why most people underestimate it.

The longer you ignore this error code, the more you will damage your engine. The engine output will keep decreasing since the turbocharger cannot provide the boost it’s supposed to.

So, it’s best to solve the error code before you drive around. Solving it as soon as possible is highly recommended, considering you want to keep your engine safe.

If you are having trouble diagnosing or fixing the error code, contact your dealer or an expert mechanic.

Read More-

  1. How to Fix P229F Code 6.7 Cummins
  2. P2459 Code 6.7 Cummins- Meaning, Causes, and Solutions


What does turbo lag mean?

In a turbocharged engine, “turbo lag” refers to the time between mashing the throttle and experiencing the torque rush. It is due to the delay in the engine’s ability to produce the correct amount of exhaust pressure to spin the turbo and send compressed air into the engine.

Do turbos require more maintenance?

Turbos require a lot more maintenance than non-turbo vehicles. Turbocharged engines need more oil changes and spark plugs than non-turbocharged ones.

Is the 6.7 Cummins a good engine?

Yes, the 6.7 Cummins engine is a good engine. But the Cummins 6.7L diesel engine is more susceptible to turbocharger problems and EGR system failures. It can, however, run from 250,00 to 350,000 miles if it is maintained properly.


The P226C code 6.7 Cummins indicates turbo lag, which means there is a time delay between using the accelerator pedal and the vehicle actually accelerating.

This is caused by a faulty turbo actuator or the turbocharger itself. Repairing them is quite impossible. So, replacing them is the only option.

This error also means you will get less output from your engine. So, driving around without resetting the code is not a good idea.


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