DTC U0073; U0100; U0121; U0131; U0155; U0214; 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 U0073:00	CAN system communication error (HS CAN)
DETECTION CONDITION	Under the following condition, a communication error (HS CAN) occurs: Battery voltage is 10 V or more.
FAIL-SAFE FUNCTION	Inhibits learning control. Inhibits neutral idle control. Inhibits AAS.
POSSIBLE CAUSE	CAN bus communication line malfunction (HS CAN) TCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0100:00	Communication error to PCM (HS CAN)
DETECTION CONDITION	Under the following condition, the TCM cannot receive the signal from PCM (HS CAN): Battery voltage is 10 V or more.
FAIL-SAFE FUNCTION	Inhibits learning control. Inhibits neutral idle control. Inhibits AAS.
POSSIBLE CAUSE	CAN communication line malfunction between PCM and TCM (HS CAN) TCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0121:00	Communication error to DSC HU/CM
DETECTION CONDITION	Under the following condition, the TCM cannot receive the signal from DSC HU/CM: Battery voltage is 10 V or more.
FAIL-SAFE FUNCTION	Inhibits learning control. Inhibits neutral idle control. Inhibits AAS.
POSSIBLE CAUSE	CAN communication line malfunction between TCM and DSC HU/CM TCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0131:00	Communication error to EPS control module
DETECTION CONDITION	Under the following condition, the TCM cannot receive the signal from EPS control module: Battery voltage is 10 V or more.
FAIL-SAFE FUNCTION	Inhibits learning control. Inhibits neutral idle control.
POSSIBLE CAUSE	CAN communication line malfunction between TCM and EPS control module TCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0155:00	Communication error to instrument cluster
DETECTION CONDITION	Under the following condition, the TCM cannot receive the signal from instrument cluster: Battery voltage is 10 V or more.
FAIL-SAFE FUNCTION	Inhibits learning control. Inhibits manual mode. Inhibits neutral idle control.
POSSIBLE CAUSE	CAN communication line malfunction between TCM and instrument cluster TCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0214:00	Communication error to start stop unit
DETECTION CONDITION	Under the following condition, the TCM cannot receive the signal from start stop unit: Battery voltage is 10 V or more.
FAIL-SAFE FUNCTION	Inhibits direct mode.
POSSIBLE CAUSE	CAN communication line malfunction between TCM and start stop unit TCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable