Engine-CodesGeneric – U1900

U1900 Code - CAN Communication Bus Fault

Quick Answer

The U1900 code indicates a fault in the CAN (Controller Area Network) communication bus system. Common causes include Faulty Wiring: Damaged or corroded wiring connections in the CAN bus system, Faulty Control Modules: A malfunction in one of the control modules connected to the CAN bus, Software Issues: Software glitches or bugs in the vehicle's control modules. 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 indicates CAN Communication Bus Fault.
Common causes
Common causes include Faulty Wiring: Damaged or corroded wiring connections in the CAN bus system, Faulty Control Modules: A malfunction in one of the control modules connected to the CAN bus, Software Issues: Software glitches or bugs in the vehicle's control modules.
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 Aug 30, 2024
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Code U1900 Description

The U1900 code indicates a fault in the CAN (Controller Area Network) communication bus system. The CAN bus is a network that allows different modules in the vehicle to communicate with each other. When this system is compromised, it can lead to issues with various vehicle systems, including the transmission, engine, ABS, airbags, and more. This can result in poor vehicle performance, reduced fuel efficiency, and potential safety hazards.

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

Common Causes of U1900

  1. Faulty Wiring: Damaged or corroded wiring connections in the CAN bus system.
  2. Faulty Control Modules: A malfunction in one of the control modules connected to the CAN bus.
  3. Software Issues: Software glitches or bugs in the vehicle's control modules.
  4. Water Damage: Water infiltration causing corrosion in the wiring or control modules.

Symptoms of U1900

  1. Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the dashboard.
  2. Transmission Issues: Problems with shifting gears or erratic behavior in the transmission.
  3. Electrical Malfunctions: Erratic behavior in electrical components such as lights, power windows, or door locks.
  4. Inoperative Modules: Some vehicle modules may become inoperative or fail to communicate with each other.

How to Fix U1900

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific codes and pinpoint the exact cause of the communication bus fault.
  2. Inspect Wiring: Check the wiring harness for any damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Check Control Modules: Inspect all control modules connected to the CAN bus for faults or malfunctions. Replace any faulty modules.
  4. Clear Codes: Clear the codes from the vehicle's computer system after the repairs have been made.
  5. Test Drive: Take the vehicle for a test drive to ensure that the issue has been resolved and that all systems are functioning properly.

Cost to Fix U1900

The cost of repairing a CAN communication bus fault can vary depending on the extent of the damage and the specific cause of the issue. In general, the repair costs can range from $200 to $800, including parts and labor. However, it's important to note that labor rates at auto repair shops can vary, so it's recommended to get a detailed estimate from a qualified technician.

Tech Notes for U1900

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 code?

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Need Help with the Code?

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Code U1900 Information for Specific Makes

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 Code

No Frequently Asked Questions about U1900 Code found.

Discuss the causes and fixes for U1900 OBDII Code

  • car over started whith cabels battery polarized after that no longer start .broken fjuze 100 ampz , after that code u 1900 ,u 2510, u 2523

  • What model and year is your vehicle? have you tried clearing the codes?