Engine-Codes.com
Engine-Codes – Mercury – U0018 Mercury

U0018 Mercury Code - Medium Speed CAN Communication Bus (-) Shorted To Bus (+)

Quick Answer

The U0018 diagnostic trouble code (DTC) for Mercury vehicles indicates a problem with the Medium Speed Controller Area Network (CAN) communication bus. Common causes include Wiring harness damage or chafing causing a short circuit, Corrosion or moisture ingress in the CAN bus connectors, Faulty ECU or control module causing a short in the CAN bus. 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
U0018 Mercury indicates Medium Speed CAN Communication Bus (-) Shorted To Bus (+).
Common causes
Common causes include Wiring harness damage or chafing causing a short circuit, Corrosion or moisture ingress in the CAN bus connectors, Faulty ECU or control module causing a short in the CAN bus.
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
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code U0018 Mercury Description

The U0018 diagnostic trouble code (DTC) for Mercury vehicles indicates a problem with the Medium Speed Controller Area Network (CAN) communication bus. In this case, the bus negative (-) line is shorted to the bus positive (+) line. The CAN bus is a network that allows various electronic control units (ECUs) in the vehicle to communicate with each other. The medium-speed CAN bus typically handles communication between components like the powertrain control module (PCM), transmission control module (TCM), anti-lock brake system (ABS), and other critical systems.

OBDII Code U0018 Mercury - Medium Speed CAN Communication Bus (-) Shorted To Bus (+)
U0018 Mercury Code - Medium Speed CAN Communication Bus (-) Shorted To Bus (+)

Common Causes of U0018 Mercury

  1. Wiring harness damage or chafing causing a short circuit.
  2. Corrosion or moisture ingress in the CAN bus connectors.
  3. Faulty ECU or control module causing a short in the CAN bus.
  4. Incorrectly installed aftermarket electronic components interfering with the CAN bus.
  5. Vehicle collision or impact damaging the wiring or connectors.

Symptoms of U0018 Mercury

  1. Check engine light illuminated on the dashboard.
  2. Loss of communication with the transmission control module.
  3. Erratic behavior of the ABS system.
  4. Issues with shifting gears or transmission performance.
  5. Inability to communicate with other control modules in the vehicle.

How to Fix U0018 Mercury

  1. Begin by conducting a thorough visual inspection of the wiring harness and connectors along the medium-speed CAN bus.
  2. Use a multimeter to check for continuity and resistance between the positive and negative lines to identify the location of the short circuit.
  3. Repair or replace any damaged wiring, connectors, or components causing the short circuit.
  4. Clear the DTC from the vehicle's memory using a diagnostic scan tool.
  5. Perform a test drive to ensure that the communication between ECUs has been restored and that the vehicle functions properly.

Cost to Fix U0018 Mercury

The cost of repairing a U0018 DTC related to a shorted medium-speed CAN bus on a Mercury vehicle can vary depending on the extent of the damage, the specific components that need to be replaced, and the labor rates of the auto repair shop. In general, the repair costs for this issue can range from $200 to $500, including parts and labor. However, it's important to note that diagnostic time and labor rates can vary significantly, so it's advisable to contact local auto repair shops for a more accurate estimate based on your specific vehicle and location.

Need more information about the U0018 Mercury code?

Need more information on how to fix the U0018 Mercury code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0018 Mercury 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 U0018 Mercury Code

1. What are common symptoms of a U0018 OBDII code in a Mercury?

- Common symptoms include intermittent or complete loss of communication with various control modules, the illumination of the check engine light, and potential transmission shifting issues.

2. What can cause the U0018 code to appear in a Mercury?

- The U0018 code typically indicates a short circuit between the Medium Speed CAN communication bus positive and negative lines, which can be caused by damaged wiring, loose connections, or faulty control modules.

3. How do I diagnose the U0018 code in my Mercury?

- Diagnosing the U0018 code involves inspecting the CAN bus wiring for damage, checking for loose connections, and using a diagnostic scanner to communicate with the affected control modules to identify the specific issue.

4. Can a U0018 code be triggered by a faulty control module in a Mercury?

- Yes, a faulty control module can cause the U0018 code to appear if it is shorting the Medium Speed CAN communication bus positive and negative lines. Replacing the faulty module may be necessary to resolve the issue.

5. Are there any repair tips for fixing the U0018 code in a Mercury?

- Repair tips for the U0018 code include carefully inspecting the wiring harness for damage, ensuring all connections are secure, and using a multimeter to check for continuity and shorts in the CAN bus circuit.

6. Is it safe to drive my Mercury with a U0018 code present?

- It is not recommended to drive your Mercury with a U0018 code present, as it can lead to communication issues between various control modules and potentially affect the vehicle's performance and safety systems.

7. How much does it typically cost to repair a U0018 code in a Mercury?

- The cost of repairing a U0018 code in a Mercury can vary depending on the underlying cause of the issue, but it may involve replacing damaged wiring, repairing connections, or replacing faulty control modules, which can range from a few hundred to a few thousand dollars.

8. Can a DIY enthusiast fix a U0018 code in a Mercury?

- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to diagnose and repair a U0018 code in a Mercury by following repair manuals, online guides, and utilizing diagnostic equipment.

9. Will resetting the OBDII code clear the U0018 code in a Mercury?

- Resetting the OBDII code may temporarily clear the U0018 code, but if the underlying issue causing the code is not addressed, it is likely to reappear once the vehicle is driven and the system detects the fault again.

10. How urgent is it to address a U0018 code in a Mercury?

- It is recommended to address a U0018 code in a Mercury as soon as possible to prevent potential communication issues between control modules, performance issues, and further damage to the vehicle's electrical system.

Discuss the causes and fixes for U0018 Mercury OBDII Code

Submit a New Comment

Code U0018 Mercury comments

No comments found for this page.