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Engine-Codes – Mercury – U1900 Mercury

U1900 Mercury Code - CAN Communication Bus Fault

Quick Answer

The U1900 code for Mercury vehicles indicates a CAN communication bus fault. Common causes include Damaged wiring harnesses, Loose connections or corroded terminals, Faulty ECUs. 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
U1900 Mercury indicates CAN Communication Bus Fault.
Common causes
Common causes include Damaged wiring harnesses, Loose connections or corroded terminals, Faulty ECUs.
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 U1900 Mercury Description

The U1900 code for Mercury vehicles indicates a CAN communication bus fault. The Controller Area Network (CAN) is a system used in modern vehicles to allow various electronic control units (ECUs) to communicate with each other. When this code is triggered, it means that there is a communication error within the CAN network, which can lead to issues with the vehicle's performance and functionality.

OBDII Code U1900 Mercury - CAN Communication Bus Fault
U1900 Mercury Code - CAN Communication Bus Fault

Common Causes of U1900 Mercury

  1. Damaged wiring harnesses
  2. Loose connections or corroded terminals
  3. Faulty ECUs
  4. Water intrusion into the CAN network
  5. Software glitches or programming errors

Symptoms of U1900 Mercury

  1. Intermittent or complete loss of communication between ECUs
  2. Warning lights on the dashboard (such as ABS, airbag, or check engine light)
  3. Stalling or rough idling
  4. Erratic shifting or poor acceleration

How to Fix U1900 Mercury

  1. Begin by conducting a thorough visual inspection of the wiring harnesses and connectors in the CAN network to look for any damage, corrosion, or loose connections.
  2. Use a diagnostic scan tool to retrieve and analyze the specific communication fault codes to pinpoint the exact source of the issue.
  3. Test the ECUs within the network to identify any faulty units that may be causing the communication problem.
  4. Address any water intrusion issues by sealing off potential entry points and drying out the affected areas.
  5. Update or reprogram the software in the ECUs if necessary to resolve any programming errors contributing to the fault.

Cost to Fix U1900 Mercury

The typical repair costs for a CAN communication bus fault can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost can range from $200 to $800, including parts and labor. However, it's important to note that diagnosis time and labor rates at auto repair shops can vary significantly based on factors such as location, vehicle make and model, and engine type. It's advisable to check with local shops for a more accurate estimate tailored to your specific situation. Keep in mind that rates at dealerships or in metropolitan areas may be higher, while independent shops often offer more competitive pricing.

What does this mean?

Tech Notes for U1900 Mercury

This is typically a false/intermittent code. It can occur if:

Someone hooks up a scanner to the OBDII port while the ignition is on or while the engine is idling.

A trailer brake system is installed improperly/incorrectly on a truck with ABS (anti-lock brakes).

When is the Code Detected?

When the PCM, Brake Controller and Instrument Cluster are unable to communicate with each other at any time while the ignition switch is turned to the “Run” position, code U1900 sets in memory.

Need more information about the U1900 Mercury code?

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Need Help with the Code?

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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 U1900 Mercury Code

1. What are common symptoms of OBDII code U1900 in a Mercury related to CAN communication bus fault?

- Common symptoms include dashboard warning lights, loss of communication with vehicle modules, erratic behavior of electronic systems, and difficulty starting the vehicle.

2. What are some possible causes of OBDII code U1900 in a Mercury?

- Possible causes include damaged wiring or connectors in the CAN bus network, faulty Control Area Network (CAN) modules, water or corrosion damage, or software issues.

3. How can I diagnose the CAN communication bus fault causing code U1900 in my Mercury?

- To diagnose the issue, perform a visual inspection of wiring and connectors, use a diagnostic scanner to check for communication errors, and perform tests on individual modules within the CAN network.

4. What are the repair options for fixing OBDII code U1900 in a Mercury due to a CAN communication bus fault?

- Repair options may include repairing or replacing damaged wiring, connectors, or modules, resetting the network by disconnecting the battery, updating software, or seeking professional assistance for advanced diagnostics.

5. Can a DIY enthusiast fix the CAN communication bus fault causing code U1900 in a Mercury?

- Depending on the specific issue, some DIY enthusiasts may be able to address the problem by checking and repairing wiring connections. However, more complex issues may require professional diagnosis and repair.

6. Is it safe to continue driving with OBDII code U1900 related to a CAN communication bus fault in a Mercury?

- It is not recommended to continue driving with this issue as it can lead to further electrical problems or affect the overall performance and safety of the vehicle. It is best to address the problem promptly.

7. How can I prevent OBDII code U1900 from reoccurring in my Mercury after repairing the CAN communication bus fault?

- To prevent the code from reoccurring, regularly inspect the wiring and connectors in the CAN network, ensure proper maintenance of electronic components, and address any related issues promptly.

8. Are there any recalls or technical service bulletins related to OBDII code U1900 in Mercury vehicles?

- It is advisable to check with the manufacturer or authorized service centers for any recalls or technical service bulletins related to OBDII code U1900 and CAN communication bus faults in Mercury vehicles.

9. Can extreme weather conditions contribute to the occurrence of OBDII code U1900 in a Mercury due to CAN communication bus faults?

- Yes, extreme weather conditions such as heat, cold, or moisture can potentially affect the CAN bus network and lead to communication faults triggering code U1900 in a Mercury.

10. How long does it typically take to diagnose and repair OBDII code U1900 in a Mercury caused by a CAN communication bus fault?

- The time required for diagnosis and repair can vary depending on the complexity of the issue and the expertise of the technician. It may range from a few hours to a full day, or longer for more challenging cases.

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