U1900 – CAN Communication Bus Fault

Meaning:

Primarily a Ford code, the U1900 means the same as U0001.

Main Symptoms:

One of the U1900 code's symptoms is the Check Engine Light
The Check Engine Light coming on might be an indicator of the U1900 trouble code
  • Check Engine Light comes on
  • Vehicle may fail to start on one or few attempts
  • Key alarm may activate intermittently

Possible Causes:

  • Open in either positive or negative CAN bus circuit
  • Open in power or ground supply circuit to the module that set the code
  • Short to ground on CAN bus circuit
  • Low voltage
  • Problem with TIPM

Diagnostic Steps:

  • Using a bidirectional scan tool, operate each module independently to find out which one is not working
  • Once you’ve pinpointed the module check that its circuits have no loose, open, broken or disconnected wires and connectors
  • Do the same for TIPM
  • Use an ohmmeter to check continuity on wire terminals in the module and TIPM
  • If all the above don’t work replace the TIPM

Read More: OBD2 Codes List: Meaning, Fixes, and Free Download