Engine-CodesMercedes-Benz – P0231 Mercedes-Benz

P0231 Mercedes-Benz Code - Fuel Pump Secondary Circuit Low

Quick Answer

The P0231 code for Mercedes-Benz specifically refers to a fault in the fuel pump secondary circuit, indicating that there is a low voltage condition present. Common causes include Faulty fuel pump relay, Corroded or damaged wiring in the fuel pump circuit, Loose or damaged connectors in the fuel pump circuit. 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
P0231 Mercedes-Benz indicates Fuel Pump Secondary Circuit Low.
Common causes
Common causes include Faulty fuel pump relay, Corroded or damaged wiring in the fuel pump circuit, Loose or damaged connectors in the fuel pump circuit.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P0231 Mercedes-Benz Description

The P0231 code for Mercedes-Benz specifically refers to a fault in the fuel pump secondary circuit, indicating that there is a low voltage condition present. The fuel pump secondary circuit is responsible for providing power to the fuel pump, which is essential for delivering fuel from the tank to the engine. When this circuit is not functioning properly, it can lead to various performance issues and potentially cause long-term damage to the vehicle.

OBDII Code P0231 Mercedes-Benz - Fuel Pump Secondary Circuit Low
P0231 Mercedes-Benz Code - Fuel Pump Secondary Circuit Low

Common Causes of P0231 Mercedes-Benz

  1. Faulty fuel pump relay
  2. Corroded or damaged wiring in the fuel pump circuit
  3. Loose or damaged connectors in the fuel pump circuit
  4. Failing fuel pump drawing excessive current
  5. Electrical issues in the vehicle's wiring system

Symptoms of P0231 Mercedes-Benz

  1. Hard starting or difficulty starting the vehicle
  2. Engine stalling or cutting out while driving
  3. Hesitation or lack of power during acceleration
  4. Rough idling or uneven engine performance
  5. Decreased fuel efficiency

How to Fix P0231 Mercedes-Benz

  1. Begin by conducting a visual inspection of the fuel pump relay, wiring, and connectors to look for any obvious signs of damage or corrosion.
  2. Test the fuel pump relay using a multimeter to ensure it is functioning correctly. Replace the relay if necessary.
  3. Check the wiring and connectors for continuity and proper voltage levels. Repair or replace any damaged components as needed.
  4. Test the fuel pump itself to determine if it is drawing excessive current or failing. Replace the fuel pump if it is found to be the cause of the low voltage condition.
  5. Clear the diagnostic trouble codes from the vehicle's computer system and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0231 Mercedes-Benz

The typical repair costs for addressing a P0231 code in a Mercedes-Benz can range from $200 to $500, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Most auto repair shops commonly charge between $80 and $150 per hour; however, rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less. It is advisable to check local rates for a more precise estimate before proceeding with the repair.

When is the Code Detected?

The code will be set if a low voltage on the control circuit of the fuel pump relay is detected by the ECM.

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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 P0231 Mercedes-Benz Code

1. What does the OBDII code P0231 mean on a Mercedes-Benz?

P0231 indicates a "Fuel Pump Secondary Circuit Low," meaning the fuel pump relay or wiring in the secondary circuit is experiencing low voltage or a malfunction.

2. What are the common symptoms of code P0231 in a Mercedes-Benz?

Symptoms include engine stalling, difficulty starting, reduced engine performance, and in some cases, the engine may not start at all.

3. What causes the P0231 code in a Mercedes-Benz?

Common causes include a faulty fuel pump relay, damaged wiring or connectors in the fuel pump circuit, a failing fuel pump, or issues with the powertrain control module (PCM).

4. Can a bad fuel pump cause the P0231 code to appear?

Yes, a failing or completely non-functional fuel pump can lead to insufficient voltage in the secondary circuit, triggering the P0231 code.

5. How can I diagnose the P0231 code on my Mercedes-Benz?

Start by inspecting the fuel pump relay, wiring, and connectors for damage or corrosion. Use a multimeter to check voltage and continuity in the circuit, and test the fuel pump for proper operation.

6. Is it safe to drive a Mercedes-Benz with the P0231 code?

Driving with P0231 is not recommended, as it can lead to engine stalling or failure to start, posing a safety risk.

7. How do I fix the P0231 code on a Mercedes-Benz?

Repairs may include replacing a faulty fuel pump relay, repairing or replacing damaged wiring or connectors, or replacing the fuel pump if necessary.

8. Can a blown fuse cause the P0231 code in a Mercedes-Benz?

Yes, a blown fuse in the fuel pump circuit can disrupt voltage and trigger the P0231 code.

9. Will clearing the P0231 code solve the issue?

Clearing the code without addressing the underlying problem will not fix the issue. The code will likely reappear until the fault is resolved.

10. How much does it cost to repair the P0231 code on a Mercedes-Benz?

Repair costs vary depending on the issue. Replacing a fuel pump relay may cost $50-$150, while fuel pump replacement can range from $300 to $800 or more, including labor.

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