Engine-CodesMercedes-Benz – P0656 Mercedes-Benz

P0656 Mercedes-Benz Code - Fuel Level Output Circuit Malfunction

Quick Answer

The P0656 code for Mercedes-Benz indicates a Fuel Level Output Circuit Malfunction. Common causes include Faulty fuel level sensor, Damaged wiring or connectors in the fuel level circuit, Corrosion or contamination in the fuel tank. 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
P0656 Mercedes-Benz indicates Fuel Level Output Circuit Malfunction.
Common causes
Common causes include Faulty fuel level sensor, Damaged wiring or connectors in the fuel level circuit, Corrosion or contamination in the fuel tank.
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 12, 2024
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Code P0656 Mercedes-Benz Description

The P0656 code for Mercedes-Benz indicates a Fuel Level Output Circuit Malfunction. This means that there is an issue with the fuel level sensor or its circuitry, which is responsible for sending information about the amount of fuel in the tank to the vehicle's computer system. This data is crucial for the accurate display of the fuel level on the dashboard and for the proper functioning of the fuel gauge.

OBDII Code P0656 Mercedes-Benz - Fuel Level Output Circuit Malfunction
P0656 Mercedes-Benz Code - Fuel Level Output Circuit Malfunction

Common Causes of P0656 Mercedes-Benz

  1. Faulty fuel level sensor
  2. Damaged wiring or connectors in the fuel level circuit
  3. Corrosion or contamination in the fuel tank
  4. Issues with the vehicle's computer system
  5. Electrical problems such as a blown fuse or relay

Symptoms of P0656 Mercedes-Benz

  1. Inaccurate fuel level readings on the dashboard
  2. Fluctuating fuel gauge readings
  3. Check Engine Light illuminated
  4. Engine stalling or misfiring
  5. Difficulty starting the vehicle

How to Fix P0656 Mercedes-Benz

  1. Diagnose the issue by using a scan tool to read the code and inspecting the fuel level sensor and its circuitry.
  2. Test the fuel level sensor for proper operation and resistance values.
  3. Check the wiring and connectors for any damage or corrosion, repairing or replacing as needed.
  4. Clear the code from the vehicle's computer and reset the system to see if the issue persists.
  5. If the problem continues, consider replacing the fuel level sensor or seeking professional help for further diagnostics.

Cost to Fix P0656 Mercedes-Benz

The typical repair costs for a Fuel Level Output Circuit Malfunction can vary depending on the extent of the issue and the specific repairs needed. In general, replacing a faulty fuel level sensor can cost between $150 and $300, while addressing wiring or electrical issues may range from $100 to $200. Labor costs can add an additional $80 to $150 per hour, with total repair costs potentially amounting to $300 to $600 or more. It's important to factor in the diagnosis time and labor rates at your local auto repair shop, as these can influence the final cost of the repair.

When is the Code Detected?

If the fault detection circuit senses a voltage other than what the PCM expects, the fault line status changes causing the P0656 code will set.

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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 P0656 Mercedes-Benz Code

1. What does the OBDII code P0656 mean on a Mercedes-Benz?

P0656 indicates a "Fuel Level Output Circuit Malfunction," meaning there’s an issue with the circuit that sends the fuel level information from the fuel tank to the instrument cluster or ECM.

2. What are the common symptoms of code P0656 in a Mercedes-Benz?

Common symptoms include an inaccurate or non-functional fuel gauge, the fuel level warning light staying on, or erratic fuel level readings.

3. What causes the P0656 code to appear in a Mercedes-Benz?

The most common causes are a faulty fuel level sensor, damaged wiring or connectors in the fuel level circuit, or a malfunctioning instrument cluster.

4. Can driving with a P0656 code cause further damage to my Mercedes-Benz?

While the code itself may not cause immediate damage, relying on inaccurate fuel readings can lead to running out of fuel unexpectedly, potentially stranding you or damaging the fuel pump.

5. How do you diagnose a P0656 code in a Mercedes-Benz?

Diagnosis typically involves checking the wiring and connectors for damage, testing the fuel level sensor with a multimeter, and verifying the functionality of the instrument cluster or ECM.

6. Can a bad fuel pump trigger the P0656 code?

While uncommon, a bad fuel pump could potentially impact the fuel level sensor if they are integrated into the same assembly, leading to this code.

7. How much does it cost to fix a P0656 code on a Mercedes-Benz?

Repair costs can vary, but replacing a fuel level sensor typically costs between $200 and $600, depending on labor rates and part prices.

8. Can I reset the P0656 code without fixing the problem?

Clearing the code with a scan tool may temporarily remove it, but if the underlying issue isn’t addressed, the code will likely return.

9. Is fixing the P0656 code a DIY-friendly repair?

For experienced DIYers, replacing the fuel level sensor or inspecting wiring may be manageable, but accessing the fuel tank or circuit components can be challenging and may require professional help.

10. What tools are needed to diagnose and repair the P0656 code?

Essential tools include an OBDII scan tool, a multimeter for testing electrical circuits, and potentially a service manual for your specific Mercedes-Benz model.

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