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The P00AF code is one of many trouble codes that may be logged by your car’s primary computer. Read on to learn more about it, its potential triggers, common symptoms, and more.

What Does the P00AF Code Mean?

Diagnostic trouble code (DTC) P00AF stands for “Turbocharger/Supercharger Boost Control A Module Performance.” This error code is logged when the powertrain control module (PCM) detects a potential issue with the boost control module. 

The “A” in this error code may refer to a potential issue in a certain portion of the system circuit instead of a specific component or symptom.

This code is often set in newer car vehicles (e.g., Cummins-powered trucks) equipped with variable geometry turbocharger (VGT) systems. In VGT systems, the PCM uses an actuator to control and monitor the turbocharger and the amount of boost it provides.

The actuator is considered a “boost control module” because it’s a smart device that communicates with the PCM over a data network. When the actuator detects an internal error, it reports the problem to the PCM. The PCM then turns on the check engine light and stores code P00AF in its memory. 

pcm detecting problem in the car system P00AF
In VGT systems, the PCM uses an actuator to control and monitor the turbocharger and the amount of boost it provides.

On some vehicles (e.g., Volkswagen), the PCM may also set P00AF if it detects a fault within the boost control system. The issue could point to anything from a damaged vacuum hose to a faulty turbocharger.

For a technical understanding of VGT systems and to see where its parts are located, you may read our discussion here. If you want to jump to the possible causes of P00AF, click here.

Note: The definition of code P00AF may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

Variable Geometry Turbocharging (VGT)

Variable Geometry Turbocharging first appeared in the early 2000s, with the original VGTs controlled directly by the ECM/PCM. Duramax and Powerstroke engines have almost the same VGT, with a special oil piston that uses engine oil pressure to control the vanes. 

When the vanes rotate to restrict exhaust, the turbo spins faster, but acts like a smaller turbo. When the vanes open, the turbo spins slower but acts like a larger capacity turbocharger. 

Cummins uses a simpler type of VGT that moves a central shaft to physically make the turbocharger smaller or larger.

Later VGT equipped engines have a dedicated VGT module that controls the geometry of the turbocharger based on its communications with the ECM/PCM via the CAN bus. These “boost control modules” are some smart boxes that will only respond to ECM/PCM commands under certain circumstances. For just one example, if the VGT module on a 6.4L Powerstroke gets too hot, it won’t respond to the ECM/PCM commands until ECM/PCM takes measures to cool the module down. The 6.4L Ford VGT is pictured here.

Variable Geometry Turbocharging by Richard McCuistian
6.4L Ford VGT showing the Variable Geometry Turbocharger and VGT Module. Image by Richard McCuistian.

What are the Possible Causes of the P00AF Code?

P00AF is a generic code, so it can have several triggers. Here are the most common:

What are the Common Symptoms of the P00AF Code?

You may notice the following symptoms if you drive a car that has a logged trouble code P00AF:

How to Diagnose the P00AF Code

To avoid the possibility of engine damage, code P00AF should be resolved immediately. However, it may be difficult to pinpoint the exact cause of the problem because there are many possible triggers associated with this code.

Keep in mind that the diagnostic and repair steps of this code should depend on the specifications of your vehicle. As all cars are built differently, they may require vehicle-specific diagnostic processes.

For instance, P00AF code on a Dodge may be diagnosed differently from a code P00AF on a Volkswagen. As such, always refer to a repair manual before attempting anything. If you’re still uncertain of how to proceed after reading the repair manual, it might be best to leave the diagnosis to a professional.

How to Fix the P00AF Code

Code P00AF may be set in vehicles of varying makes and models. It may share similar causes and symptoms with other DTCs. However, since cars differ depending on the manufacturer, there is no one-size-fits-all solution for this code.

All vehicles are different, so you should always refer to the factory repair information specific to your car before DIY-ing any repairs. However, if you aren’t confident in your automotive repair skills, it may be best to bring your vehicle to an auto repair shop for proper diagnosis and repair.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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