P0238 Code: Turbocharger / Supercharger Boost Sensor A Circuit High

If you’re using an OBD-II scanner and it registers a P0238 code, your vehicle might have issues with its turbocharger or supercharger. In this guide, you’ll learn more about diagnosing and troubleshooting the P0238 code.

What Does the P0238 Code Mean?

The P0238 code is defined as “Turbocharger/Supercharger Boost Sensor ‘A’ Circuit High.” Many modern vehicles are equipped with a turbocharger or supercharger to improve engine performance and efficiency.

For just one example, on a 2018 Camaro, code P0238 is set when the ECM detects that the boost pressure sensor voltage is greater than 3.9 V for greater than 5 seconds.

The Boost Pressure Sensor lets the powertrain control module (PCM) know how much boost the turbocharger creates. If the PCM logs a wrong signal from the Boost Pressure Sensor or it detects too much boost from a turbocharger, the PCM might set code P0238.

Make sure you have an in-depth background about turbochargers and superchargers if you plan to diagnose or fix P0238 yourself.

A Closer Look at the Boost Pressure Sensor

The boost sensor is a feedback signal giving the ECM/PCM information on manifold pressure for the purpose of preventing over-boost and to add data for the fuel injection and timing algorithms during boost.

This is the circuit description on a 2018 Camaro:

The boost pressure sensor is integrated with the Turbocharger Boost/Intake Air Temperature sensor and measures the range of pressures between the turbocharger and the throttle body. Pressure in this portion of the induction system is affected by engine speed, throttle opening, turbocharger boost pressure, Intake air temperature (IAT), barometric pressure (BARO), and the efficiency of the charge air cooler.

The boost pressure sensor is integrated with the Turbocharger Boost/Intake Air Temperature sensor and measures the range of pressures between the turbocharger and the throttle body.

– Richard McCuistian, ASE Certified Master Automobile Technician

The boost pressure sensor provides a signal voltage to the engine control module (ECM), relative to the pressure changes. Under normal operation the greatest pressure that can exist in this portion of the induction system at ignition ON engine OFF is equal to the BARO. When the engine is operated at wide-open throttle (WOT) the turbocharger can increase the pressure to near 240 kPa (34.8 psi). The pressure is equal to the BARO when the engine is idling or decelerating.

Note: The P0238 code may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0238 Code?

There are several issues that can cause the P0238 code to trigger. These include the following:

• Failed boost pressure sensor
• Turbocharger or supercharger failure
• Wiring issue
• Triggered OBD-II code related to intake air temperature sensor (IAT)
• Triggered OBD-II code related to engine coolant temperature sensor (ECT)

What are the Possible Symptoms of the P0238 Code?

When the P0238 is triggered, the PCM will ignore the voltage coming from the boost control solenoid. Instead, it assigns a general value for the boost pressure. When this happens, your vehicle may exhibit the following symptoms:

• Decreased engine performance
• Limp mode enabled
• Increased fuel consumption
• Lack of boost from the turbocharger or supercharger

How to Diagnose the P0238 Code

The P0238 code can be caused by several issues. However, accurately identifying the faulty part can be difficult, especially if you don’t know what to look for. Also, accessing certain components can be tricky without the right tools and experience. If you want to properly diagnose what’s causing the code to trigger, then we recommend consulting a trusted mechanic.

The following video might give you a better idea of the diagnostic process:

How to Fix the P0238 Code 

Unfortunately, there isn’t a single umbrella solution for the P0238 code. Since each vehicle is different, solving issues that set this specific code will vary from vehicle to vehicle. To determine the right repair procedure, you must first get an accurate diagnosis.

Once you’ve figured out the root cause of the P0238 code, then you can look up credible online repair resources and how-to guides for possible solutions. Always consult your vehicle’s repair manual when it comes to troubleshooting and repairing diagnostic codes.

Consulting Chilton repair manuals can be useful. ALLDATA subscriptions are even better, as they provide detailed factory repair information for drivers who want to do repairs themselves. If you aren’t an expert in automotive repair, it might be best to leave it to a professional.

Fix the P0238 Code With a New Boost Pressure Sensor

The P0238 code is triggered because of issues with your turbocharger or supercharger. A faulty boost pressure sensor can also be to blame. If these problems aren’t properly addressed, your vehicle can develop engine performance issues. Getting a new boost pressure sensor should restore your vehicle. Luckily, getting a replacement boost sensor is quick and easy here at CarParts.com.

Whether you need a fuel pump, boost pressure sensor, or fuel temperature sensor, CarParts.com has you covered. We source parts from only the most trusted manufacturers in the industry so you know they’ll fit properly and perform reliably. Our strategically located warehouses also means you can get your order in as fast as two business days.

Reliability is paramount when it comes to sensors. Rest assured that you’re getting the best when you shop for a boost pressure sensors here at CarParts.com today!