Advanced Diagnostics

Advanced Diagnostics - DTC U0122: F-CAN Malfunction (Engine Control Module (ECM)-VSA Modulator-Control Unit) (PGM-FI System (Engine Type: K24Z7))

General Description






The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (F_CAN-H and F_CAN-L). When the information is not sent from the VSA modulator-control unit via the F-CAN lines and this condition continues for a specified time or when the information sent from the VSA modulator-control unit is abnormal and this condition continues for a specified cycle, the engine control module (ECM) detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
One of these conditions is met:
- The ECM does not receive any signals via the F-CAN lines for at least 1 second.
- The information sent from the VSA modulator-control unit is abnormal at least 20 times.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

- VSA modulator-control unit failure (include fuse fall-outs)
- F-CAN circuit F_CAN-H line open
- F-CAN circuit F_CAN-L line open
- F-CAN circuit F_CAN-H line short to ground
- F-CAN circuit F_CAN-L line short to ground
- ECM internal circuit failure

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected, a Pending DTC, a Confirmed DTC, and the freeze data are stored in the ECM memory. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.