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DTC U0401: Engine CAN Message
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be stored. Prior to this diagnosis, diagnose the CAN bus lines.
  • Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
 
 
OPERATION
AWC-ECU communicates with the engine control module via the CAN bus lines.
 
 
DTC SET CONDITION
This DTC is stored when the abnormality below is detected:
  • Abnormality is detected in the signal received from the engine control module.
 
 
PROBABLE CAUSES
  • Malfunction of the CAN bus line
  • Engine malfunction
  • Malfunction of engine control module
  • Malfunction of AWC-ECU

 
 
DIAGNOSTIC PROCEDURE
STEP 1. Scan tool (M.U.T.-III) CAN bus diagnostics.
Use scan tool (M.U.T.-III) to perform the CAN bus diagnosis.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Diagnosis, Can Bus Diagnostics Table ).
 
STEP 2. Scan tool (M.U.T.-III) DTC.
Check the engine DTC (Refer to GROUP 13A - Diagnosis, Diagnostic Trouble Code Chart ).
Is the DTC stored?
Perform the relevant troubleshooting.
Go to Step 3.
 
STEP 3. Scan tool (M.U.T.-III) data list.
Check the following data list (Refer to ).
  • Item No.12: Engine speed
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Go to Step 4.
 
STEP 4. Check whether the DTC is stored again.
Is DTC No.U0401 stored?
Replace the AWC-ECU (Refer to ). Then go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
 
STEP 5. Check whether the DTC is stored again.
Is DTC No.U0401 stored?
Return to Step 1.
This diagnosis is complete.