DTC U0156-00: Communication Error With Connectivity Master Unit (CMU) [Vehicle Control Module]: Outline

WARNING: This page is about a different car, the 2021 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

DTC U0156:00 [VEHICLE CONTROL MODULE] DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	Communication error with connectivity master unit (CMU)
Detection condition	The vehicle control module (VCM) cannot receive CAN signal from connectivity master unit (CMU) for 10 s.
Fail-safe	(See DTC TABLE [VEHICLE CONTROL MODULE (US)] .)
Possible cause	Malfunction in CAN communication line between vehicle control module (VCM) and connectivity master unit (CMU) Connectivity master unit (CMU) malfunction Vehicle control module (VCM) malfunction (built into body control module (BCM)) Body control module (BCM) malfunction
System wiring diagram	Not applicable