AutoCodes – Mercedes-Benz – P0238 Mercedes-Benz

P0238 Mercedes-Benz Code - Turbocharger/Supercharger Boost Sensor 'A' Circuit High

Quick Answer

The Boost Pressure Sensor responds to pressure changes in the intake manifold. Common causes include Faulty Boost Pressure Sensor, Boost Pressure Sensor harness is open or shorted, Boost Pressure Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0238 Mercedes-Benz indicates Turbocharger/Supercharger Boost Sensor 'A' Circuit High.
Common causes: Common causes include Faulty Boost Pressure Sensor, Boost Pressure Sensor harness is open or shorted, Boost Pressure Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 21,813

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 11, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0238 Mercedes-Benz Description

The Boost Pressure Sensor responds to pressure changes in the intake manifold. This pressure is created by the turbocharger and changes with Accelerator Pedal Position (APP) and engine speed. The Engine Control Module (ECM) uses this information to assist in the diagnosis of the Barometric Pressure (BARO) sensor and to provide engine over-boost protection. The boost pressure sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The ECM supplies 5 volts to the boost pressure sensor on the 5-volt reference 2 circuit and provides a ground on a low reference circuit. The boost pressure sensor provides a signal to the ECM on a signal circuit relative to the pressure changes. The ECM monitors the boost pressure sensor signal for voltage outside of the normal range. The ECM calculates a predicted value for the boost pressure sensor. The ECM then compares the predicted value to the actual signal. This Diagnostic Trouble Code (DTC) P0238 will set if the boost pressure sensor signal is above the predicted range.

OBDII Code P0238 Mercedes-Benz - Turbocharger/Supercharger Boost Sensor 'A' Circuit High - AutoCodes.com — P0238 Mercedes-Benz Code - Turbocharger/Supercharger Boost Sensor 'A' Circuit High

What does this mean?

What are the Possible Causes of the DTC P0238 Mercedes-Benz?

Faulty Boost Pressure Sensor
Boost Pressure Sensor harness is open or shorted
Boost Pressure Sensor circuit poor electrical connection
Faulty Engine Control Module (ECM)
Engine over temperature

How to Fix the DTC P0238 Mercedes-Benz?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0238 Mercedes-Benz code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0238 Mercedes-Benz code?

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Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0238 Mercedes-Benz Code

1. What does the OBDII code P0238 mean for a Mercedes-Benz?

The P0238 code indicates that the Turbocharger/Supercharger Boost Sensor 'A' Circuit is reading a voltage that is higher than the manufacturer-specified range.

2. What are the common symptoms of code P0238 in a Mercedes-Benz?

Symptoms may include reduced engine power, poor acceleration, the Check Engine Light turning on, and potentially entering limp mode.

3. What causes the P0238 code to appear in a Mercedes-Benz?

Common causes include a faulty boost pressure sensor, damaged sensor wiring or connectors, a short circuit, or excessive turbocharger boost pressure.

4. Can I drive my Mercedes-Benz with the P0238 code present?

While the car may still be drivable, it's not recommended as the issue could cause additional engine damage or unsafe driving conditions due to reduced power.

5. How do I diagnose the P0238 code on a Mercedes-Benz?

Diagnose the issue by checking the boost pressure sensor, inspecting the wiring and connectors for damage, and using a scan tool to monitor live sensor data.

6. How can I fix the P0238 code on my Mercedes-Benz?

Repairs may include replacing the boost pressure sensor, repairing damaged wiring or connectors, or recalibrating the ECM if necessary.

7. Does the P0238 code always mean the boost sensor is faulty?

No, the issue could also be caused by wiring problems, a malfunctioning turbocharger, or even an ECM issue rather than the sensor itself.

8. How much does it cost to fix the P0238 code on a Mercedes-Benz?

Repair costs can range from $100 to $300 for a boost pressure sensor replacement, but additional costs may arise if wiring or turbocharger issues are present.

9. Can a dirty air filter cause the P0238 code in a Mercedes-Benz?

A dirty air filter is unlikely to directly cause this code, but it can contribute to turbocharger or boost performance issues over time.

10. Is the P0238 code specific to Mercedes-Benz vehicles?

No, the P0238 code is a generic OBDII code that can appear on various vehicles, but the diagnostic and repair steps may differ slightly for Mercedes-Benz models.