S-AWC

DTC U0401: Engine Data Error

CAUTION
^ If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code 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 code is set when abnormality is detected in the signal received from the engine control module.

PROBABLE CAUSES
^ The CAN bus line is defective.
^ Engine malfunction
^ Malfunction of AWC-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 2.
NO: Repair the CAN bus lines.

STEP 2. Scan tool diagnostic trouble code
Check the engine diagnostic trouble code. Diagnostic Trouble Code Descriptions
Q: Is the DTC set?
YES: Perform the relevant troubleshooting.
NO: Go to Step 3.

STEP 3. Scan tool service data
Check the following service data. (Data List Reference Table)
^ Item No. 15: Engine speed
^ Item No. 16: Engine torque (Driver request value)
Q: Is the check result normal?
YES: Intermittent malfunction.
NO: Go to Step 4.

STEP 4. Check whether the DTC is reset.
Q: Is DTC No. U0401 set?
YES: Replace the AWC-ECU. Then go to Step 5.
NO: Intermittent malfunction.

STEP 5. Check whether the DTC is reset.
Q: Is DTC No. U0401 set?
YES: Return to Step 1.
NO: This diagnosis is complete.