Code No. U1801: Airbag communication line short

  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be stored. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.


The PHEV-ECU stores diagnosis code No. U1801 when it cannot communicate with the SRS-ECU correctly.


  • Damaged harness or connector
  • Malfunction of SRS-ECU
  • Malfunction of PHEV-ECU


1. Check the signal line for open and short circuit. (PHEV-ECU and the SRS-ECU)

  • Check the wiring harness between brake PHEV-ECU connector (ARBS terminal) and the SRS-ECU (ARBS terminal) connector.
2.Check whether the diagnosis code is stored again.
3.Replace the SRS-ECU, and check whether the diagnosis code is stored again.

  • If the diagnosis code is not erased, replace the PHEV-ECU (Refer to ).