DTC U0401; Error Signal Received From Pcm: Notes

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

DETECTION CONDITION & POSSIBLE CAUSE

Description	Error signal received from PCM
Detection condition	Communication error between PCM and radar unit
Fail-safe	Inhibits the mazda radar cruise control (MRCC) system control Inhibits the smart brake support (SBS) system control Inhibits the distance recognition support system (DRSS) control
Possible cause	DTCs are stored in the PCM. PCM malfunction Radar unit malfunction
System wiring diagram	Not applicable