AutoCodes – Mercury – U0118 Mercury

U0118 Mercury Code - Lost Communication With Fuel Additive Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Top Off Fuel Additive Tank, Faulty Fuel Additive Sensor, Faulty 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 Top Off Fuel Additive Tank, Faulty Fuel Additive Sensor, Faulty 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.

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Code Popularity 492

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 Mar 30, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0118 Mercury Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Fuel Additive Control Module has not been received.

OBDII Code U0118 Mercury - Lost Communication With Fuel Additive Control Module - AutoCodes.com — U0118 Mercury Code - Lost Communication With Fuel Additive Control Module

What does this mean?

What are the Possible Causes of the DTC U0118 Mercury?

Top Off Fuel Additive Tank
Faulty Fuel Additive Sensor
Faulty Fuel Additive Control Module
Fuel Additive Control Module harness is open or shorted
Fuel Additive Control Module circuit poor electrical connection

How to Fix the DTC U0118 Mercury?

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 U0118 Mercury 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.

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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 vehicleâ€™s control modules can sometimes cause communication errors like U0118. A software update may be required.