35C-CODE NO. U0401 ENGINE CAN MESSAGE

Code No. U0401 Engine (CAN message)

caution

If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be stored. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
Before replacing the ECU, ensure that the communication circuit is normal.
When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to and ).

OPERATION

Engine-related signals are sent or received to and from between ASC-ECU and engine ECU via CAN bus lines.

DIAGNOSTIC TROUBLE CODE SET CONDITIONS

This diagnostic trouble code is stored when the engine ECU malfunction has been detected.

PROBABLE CAUSES

DIAGNOSIS

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.

Use the scan tool MB991958 to diagnose the CAN bus lines.

Is the check result normal?

Go to Step 3

Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting

.) On completion, go to Step 2

STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines

Is diagnostic trouble code No. U0401 stored?

Go to Step 3

This diagnosis is complete.

STEP 3. Check for diagnostic trouble codes of other systems.

Check if diagnostic trouble code(s) other than U0401 is stored.

Is the diagnostic trouble code stored?

Follow the relevant diagnostic trouble code procedure, and then go to Step 5

Go to Step 4

STEP 4. Use scan tool MB991958 to confirm a diagnostic trouble code of other systems.

Check if the diagnostic trouble code is stored in the engine ECU (Refer to GROUP 13A - Diagnostic Trouble Code Chart

Is the diagnostic trouble code stored?

Troubleshoot the engine ECU diagnostic trouble code. Then go to Step 5

Go to Step 5

STEP 5. Diagnostic trouble code recheck

Check again if the diagnostic trouble code is stored.

(1) Erase the stored diagnostic trouble code.

(2) Ignition switch: "LOCK" (OFF)

(3) Ignition switch: "ON"

Is diagnostic trouble code No. U0401 stored?

Replace the hydraulic unit (integrated with ASC-ECU). (Refer to

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction