DTC U0122: F-CAN Malfunction (ECM-VSA): General Description
The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (CANH and CANL).
When the engine control module (ECM) does not receive the signals via the CAN lines for more than a set time, the ECM detects a malfunction and a DTC is stored.