DTC U0401; Can System Communication Error: 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

DTC U0401:00	CAN system communication error
DETECTION CONDITION	Error detected in signal from PCM via CAN communication
FAIL-SAFE FUNCTION	Vehicle speed signal malfunction Control is maintained by gradually changing the controlled vehicle speed and setting it to 100 km/h {62.1 mph} Power steering malfunction indicator light: Illuminated Engine speed signal malfunction Control enabled Power steering malfunction indicator light: Not illuminated
POSSIBLE CAUSE	PCM malfunction
SYSTEM WIRING DIAGRAM	-