Diagnostic Aids
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.
DTC U0121:00 indicates a possible failure of the HS-CAN which can be due to a circuit fault in the HS-CAN, the PSCM wiring harness or an ABS module concern.
Do not install a new PSCM as part of the repair for a PSCM DTC U0121:00.
The presence of DTC U0121:00 prevents the active park assist system (if equipped) and the lane keep assist function (if equipped) from activating. If set during an active park assist event, the event is terminated and the active park assist system is deactivated.