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DTC U0401: Engine Data Malfunction
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. 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 CONDITIONS
The DTC is set when 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

 
 
DIAGNOSIS
STEP 1. Scan tool (M.U.T.-IIISE) CAN bus diagnostics.
Use scan tool (M.U.T.-IIISE) 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.-IIISE) other system DTC.
Check the engine DTC (Refer to GROUP 13A - Diagnosis, Diagnostic Trouble Code Chart ).
Is the DTC set?
Perform the relevant troubleshooting.
Go to Step 3.
 
STEP 3. Scan tool (M.U.T.-IIISE) data list.
Check the following data list (Refer to ).
  • Item No.25: 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 set again.
Is the DTC U0401 set?
Replace the AWC-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).