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Engine-Codes – Mercury – U0118 Mercury

U0118 Mercury Code - Lost Communication With Fuel Additive Control Module

Quick Answer

The U0118 diagnostic trouble code (DTC) for Mercury vehicles indicates that there has been a communication failure with the Fuel Additive Control Module. Common causes include Faulty Fuel Additive Control Module: A malfunction within the Fuel Additive Control Module itself can cause communication failures, Wiring Issues: Damaged or corroded wiring connections between the module and the ECM can disrupt communication, ECM Malfunction: A malfunction within the engine control module can prevent proper communication with the Fuel Additive Control Module. 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
U0118 Mercury indicates Lost Communication With Fuel Additive Control Module.
Common causes
Common causes include Faulty Fuel Additive Control Module: A malfunction within the Fuel Additive Control Module itself can cause communication failures, Wiring Issues: Damaged or corroded wiring connections between the module and the ECM can disrupt communication, ECM Malfunction: A malfunction within the engine control module can prevent proper communication with the Fuel Additive Control Module.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 13, 2024
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Code U0118 Mercury Description

The U0118 diagnostic trouble code (DTC) for Mercury vehicles indicates that there has been a communication failure with the Fuel Additive Control Module. This module is responsible for managing the fuel additive system in the vehicle, which is designed to improve fuel efficiency and reduce emissions. When communication is lost with this module, it can lead to a variety of issues that can affect the vehicle's performance and overall operation.

OBDII Code U0118 Mercury - Lost Communication With Fuel Additive Control Module
U0118 Mercury Code - Lost Communication With Fuel Additive Control Module

Common Causes of U0118 Mercury

  1. Faulty Fuel Additive Control Module: A malfunction within the Fuel Additive Control Module itself can cause communication failures.
  2. Wiring Issues: Damaged or corroded wiring connections between the module and the ECM can disrupt communication.
  3. ECM Malfunction: A malfunction within the engine control module can prevent proper communication with the Fuel Additive Control Module.
  4. Software Glitch: Software issues within the vehicle's onboard computer systems can lead to communication errors.
  5. Electrical Interference: External factors such as electromagnetic interference can disrupt communication between modules.

Symptoms of U0118 Mercury

  1. Check Engine Light: The most common symptom associated with the U0118 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Fuel Efficiency: A noticeable decrease in fuel efficiency may occur due to the improper regulation of fuel additives.
  3. Engine Misfires: Communication issues with the Fuel Additive Control Module can lead to engine misfires or rough idling.
  4. Stalling: The vehicle may experience stalling or hesitation during acceleration due to the lack of proper fuel additive control.

How to Fix U0118 Mercury

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the trouble codes and pinpoint the communication failure with the Fuel Additive Control Module.
  2. Inspect Wiring Connections: Check the wiring harness for any damage or corrosion and repair or replace as needed.
  3. Test Fuel Additive Control Module: Test the module for proper functionality and replace if it is found to be faulty.
  4. Check ECM Functionality: Ensure that the engine control module is functioning correctly and reprogram if necessary.
  5. Clear Codes and Test Drive: Clear the trouble codes from the vehicle's computer system and test drive to verify that the issue has been resolved.

Cost to Fix U0118 Mercury

The cost of repairing a U0118 code related to a lost communication with the Fuel Additive Control Module can vary depending on the specific cause of the issue and the labor rates in your area. On average, the repair cost for this type of issue can range from $200 to $500, including parts and labor. Keep in mind that additional diagnostic time may be needed to pinpoint the exact cause of the communication failure, which can affect the overall repair cost. It's recommended to consult with a qualified mechanic or auto repair shop to get an accurate estimate based on your vehicle's make and model. Labor rates at auto repair shops typically range from $80 to $150 per hour, but rates may vary based on location and shop type.

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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 U0118 Mercury Code

1. What does the OBDII code U0118 mean on a Mercury vehicle?

The U0118 code indicates that the vehicle's primary control modules have lost communication with the Fuel Additive Control Module (FACM).

2. What are the common symptoms of the U0118 code in a Mercury?

Symptoms may include the check engine light turning on, reduced fuel efficiency, and issues with the diesel particulate filter (DPF) regeneration process in diesel vehicles.

3. What causes the U0118 code to appear on a Mercury?

Common causes include a faulty Fuel Additive Control Module, damaged wiring or connectors, a blown fuse, or issues with the vehicle's CAN bus communication system.

4. Can I drive my Mercury with the U0118 code?

While it may be possible to drive, ignoring the issue can lead to further problems, such as clogged DPF or reduced engine performance. It's best to address the issue promptly.

5. How can I diagnose the U0118 code on my Mercury?

Start by inspecting the FACM wiring and connectors for damage, check for blown fuses, and use a scan tool to verify if the module is communicating with the vehicle's network.

6. What tools are needed to troubleshoot the U0118 code?

You'll need a diagnostic scan tool capable of reading manufacturer-specific codes, a multimeter for testing electrical connections, and potentially a wiring diagram for your vehicle.

7. How do you fix the U0118 code on a Mercury?

Repairs may involve replacing or repairing damaged wiring, cleaning or reconnecting connectors, replacing a blown fuse, or replacing the Fuel Additive Control Module if defective.

8. How much does it cost to fix the U0118 code on a Mercury?

The cost can vary widely depending on the issue, ranging from $50 for simple wiring repairs to $500 or more if the FACM needs replacement.

9. What happens if the U0118 code is not resolved?

If left unresolved, the DPF may not regenerate properly, leading to clogging, decreased engine performance, and potentially expensive repairs.

10. Can a software issue cause the U0118 code on a Mercury?

Yes, outdated or corrupted software in the vehicle’s control modules can sometimes cause communication errors like U0118. A software update may be required.

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