DTC U0121-00: Can Communication: Communication Error To DSC HU/Cm (Us): Outline

WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.

DTC U0121:00 (PCM, SKYACTIV-G, US) DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	CAN communication: communication error to DSC HU/CM
Detection condition	Communication error between the PCM and DSC HU/CM continues for 5 s or more.
Fail-safe	Inhibits the DSC control.
Possible cause	CAN communication line malfunction between PCM and DSC HU/CM DSC HU/CM malfunction PCM malfunction
System wiring diagram	Not applicable
Connector diagram	Not applicable