DTC U2640-14: LF Control Unit Power Supply Circuit (B1+) Malfunction (BCM): 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 U2640:14 (BCM) DETECTION CONDITION AND POSSIBLE CAUSE

System malfunction location	LF control unit power supply circuit (B1+) malfunction
Detection condition	The LF control unit detects an open circuit or short to ground in the power supply circuit (B1+).
Fail-safe	Not applicable
Possible cause	LF control unit connector or terminal malfunction Short to ground or open circuit in LF control unit power supply circuit (B1+) LF control unit malfunction Body control module (BCM) malfunction
Courtesy of MAZDA MOTORS CORP.