Code Definition

U1900 — CAN Communication Bus Fault

System: Network Communication  |  Type: Manufacturer-Specific  |  Make: Generic

About U1900

U1900 is a manufacturer-specific network communication diagnostic trouble code. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

Scanning & clearing: Network (U) codes report communication faults between modules. When diagnosing U-codes, checking the vehicle's CAN bus integrity, supply/ground at each module, and reading all modules for related faults is usually the first step.

U1900 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This DTC is a general communication fault stored by a control module when it detects a problem on the Controller Area Network (CAN) data bus. CAN is a two wire differential network, CAN High and CAN Low, that lets the vehicle modules share data such as engine speed, wheel speed, and switch states over a shared pair of twisted wires. The code sets when the module sees excessive error frames, a loss of message synchronisation, missing expected messages, or bus contention that disrupts reliable data exchange. Because so many functions depend on the bus, a driver may notice several warning lights ...

Join TaT to view the complete code information and diagnostic details.

Quick Facts