DTC U0121: Lost Communication with the Anti-lock Brake System (ABS) Control Module: Description

WARNING: This page is about a different car, the 2020 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

The PSCM monitors the HS-CAN messages when the ignition has been on for more than 5 seconds, the voltage to the PSCM is greater than 9 volts and there are no DTCs present inhibiting PSCM operation.

DTC U0121:00 (Lost Communication with the Anti-lock Brake System (ABS) Control Module: No Sub Type Information) - This DTC is set when communication between the PSCM and the ABS module fails. The ABS module sends a steering angle sensor message to the PSCM. If this message is missing for more than the allotted amount of time and the PSCM has not set DTC U0001:88, then the PSCM sets DTC U0121:00.