U1900 Code: Meaning, Causes, and Symptoms | OBD2 Codes
U1900 – CAN Communication Bus Fault
U1900 Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light),Amber ABS (Anti-lock Brakes) Light ON,Wrench Light On
U1900 Possible Causes
Faulty / intermittent ignition switch connections,CAN Bus wiring intermittently open/shorted to power or ground,Faulty / intermittent connection at PCM,Faulty electrical connections at ABS Control Module,Faulty electrical connections at the instrument cluster,Poor connections at the trailer brake controller/trailer connector
The Anti-ock Brakes System (ABS) module, the Powertrain Control Module (PCM), and the instrument cluster communicate over the Controller Area Network (CAN) Bus. This is a high-speed bus communication system and is not fault tolerant, which means any type of intermittent/loose connection between these 3 controllers will cause communication to stop. When the PCM, ABS module and instrument cluster are unable to communicate with each other at any time while the ignition switch is turned on, code U1900 will set.