AutoCodes – Mercedes-Benz – P0231 Mercedes-Benz

P0231 Mercedes-Benz Code - Fuel Pump Secondary Circuit Low

Quick Answer

The Engine Control Module (ECM) provides ignition positive voltage to the coil side of the fuel pump relay. Common causes include Blown Fuel Pump fuse, Open Fuel Pump Monitor Circuit, Faulty Fuel Pump Relay. 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 Blown Fuel Pump fuse, Open Fuel Pump Monitor Circuit, Faulty Fuel Pump Relay.
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 3,816

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 Apr 13, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0231 Mercedes-Benz Description

The Engine Control Module (ECM) provides ignition positive voltage to the coil side of the fuel pump relay. When the ignition switch is first turned ON, the ECM energizes the fuel pump relay, which applies power to the fuel pump. The ECM enables the fuel pump relay as long as the engine is cranking or running, and crankshaft reference pulses are received. If no crankshaft reference pulses are received, the ECM de-energizes the fuel pump relay after 2 seconds. The ECM monitors the voltage on the fuel pump relay control circuit.

OBDII Code P0231 Mercedes-Benz - Fuel Pump Secondary Circuit Low - AutoCodes.com — P0231 Mercedes-Benz Code - Fuel Pump Secondary Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0231 Mercedes-Benz?

Blown Fuel Pump fuse
Open Fuel Pump Monitor Circuit
Faulty Fuel Pump Relay
Damaged Engine Control Module (ECM)

How to Fix the DTC P0231 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 P0231 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 P0231 Mercedes-Benz code?

Need more information on how to fix the P0231 Mercedes-Benz code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0231 Mercedes-Benz code diagnosed by a professional: Find a repair shop in your area

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.