DTC U0073; U0101; U0104; U0121; U0131; U0140; U0151; U0155; U0214; U023A; Can System Communication Errors: 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 AND POSSIBLE CAUSE

DTC U0073:00	CAN system communication error (HS CAN)
DETECTION CONDITION	Malfunction in CAN bus communication line. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Not applicable
POSSIBLE CAUSE	CAN bus communication line malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0101:00	CAN communication: communication error to TCM
DETECTION CONDITION	Communication error between the PCM and TCM continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light illuminates if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2)/Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Controls the turbine rotation signal at 0. Inhibits the AT torque reduction request.
POSSIBLE CAUSE	NOTE: During malfunction diagnosis, first verify the malfunction detection of DTC U0074:00 or U0115:00 for the TCM. CAN communication line malfunction between PCM and TCM TCM malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0104:00	CAN communication: communication error to radar unit
DETECTION CONDITION	Communication error between the PCM and radar unit continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	The radar unit function is cancelled.
POSSIBLE CAUSE	CAN communication line malfunction between PCM and radar unit Radar unit malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0121:00	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. Diagnostic support note This is a continuous monitor (other). The check engine light illuminates if the PCM detects the above malfunction condition during the first drive cycle. FREEZE FRAME DATA (Mode 2)/Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	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
DTC U0131:00	CAN communication: communication error to EPS control module
DETECTION CONDITION	Communication error between the PCM and EPS control module continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Not applicable
POSSIBLE CAUSE	CAN communication line malfunction between PCM and EPS control module EPS control module malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0140:00	CAN communication: communication error to front body control module (FBCM)
DETECTION CONDITION	Communication error between the PCM and front body control module (FBCM) continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Not applicable
POSSIBLE CAUSE	CAN communication line malfunction between PCM and front body control module (FBCM) Front body control module (FBCM) malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0151:00	CAN communication: communication error to SAS control module
DETECTION CONDITION	Communication error between the PCM and SAS control module continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Not applicable
POSSIBLE CAUSE	CAN communication line malfunction between PCM and SAS control module SAS control module malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0155:00	CAN communication: communication error to instrument cluster
DETECTION CONDITION	Communication error between the PCM and instrument cluster continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. (The check engine light may be illuminated depending on the condition.) FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Not applicable
POSSIBLE CAUSE	CAN communication line malfunction between PCM and instrument cluster Instrument cluster malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U0214:00	CAN communication: communication error to start stop unit
DETECTION CONDITION	Communication error between the PCM and start stop unit continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	Not applicable
POSSIBLE CAUSE	CAN communication line malfunction between PCM and start stop unit Start stop unit malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable
DTC U023A:00	CAN communication: communication error to forward sensing camera (FSC)
DETECTION CONDITION	Communication error between the PCM and forward sensing camera (FSC) continues for 5 s or more. Diagnostic support note This is a continuous monitor (other). The check engine light does not illuminate. FREEZE FRAME DATA (Mode 2) is not available. Snapshot data is available. DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	The smart city brake support function is cancelled.
POSSIBLE CAUSE	CAN communication line malfunction between PCM and forward sensing camera (FSC) Forward sensing camera (FSC) malfunction PCM malfunction
SYSTEM WIRING DIAGRAM	Not applicable