U1900

What does U1900 mean?

U-code U1900 means "CAN Communication Bus Fault". It is a manufacturer-specific diagnostic trouble code (DTC) in the vehicle network (CAN/LIN bus). A communication failure has been detected — the module responsible for the can communication bus fault is not responding on the vehicle network. This code can be monitored, but service is recommended to prevent escalation. This code applies to OBD-II compliant electric and hybrid vehicles.

Possible Causes

• CAN bus wiring fault (short, open, or termination resistor failure)
• Faulty control module not transmitting on the vehicle network
• Power supply issue preventing the module from initializing
• Software mismatch or corruption in the affected module

Recommended Actions

1. 1 Note the alert and schedule a diagnostic appointment when convenient
2. 2 Scan for all DTCs with an OBD-II scanner — note any related codes stored alongside U1900
3. 3 Check CAN bus wiring for damage; verify termination resistance (should be ~120 Ω between CAN-H and CAN-L)
4. 4 Verify power supply and ground connections at the affected module
5. 5 Clear the DTC, road-test the vehicle, and re-scan to confirm whether the fault returns
6. 6 If the fault persists after inspection and clearing, consult an EV-certified technician for component replacement

Related Network fault codes