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DTC U0401: Engine (CAN message)
 
 
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 (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
OPERATION
Engine-related signals are sent or received to and from between electric parking brake ECU and engine control module (ECM) via CAN bus lines.
 
 
DTC SET CONDITIONS
The DTC will be set under any of the following conditions:
  • The system receives an invalid accelerator pedal opening angle signal.
  • The system detects an implausible accelerator pedal opening angle signal.
  • The system receives an invalid engine torque signal.
  • The system detects an implausible engine torque signal.
  • The system receives an invalid engine speed signal.
  • The system detects an implausible engine speed signal.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of engine system
    • Accelerator pedal position sensor
    • Air flow sensor
    • Crank angle sensor
  • The CAN bus line is defective (noise interference).
  • Malfunction of the electric parking brake ECU
 
 
DIAGNOSIS
STEP 1. Scan tool (M.U.T.-III) CAN bus diagnosis
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.
 
STEP 2. DTC recheck after resetting CAN bus lines
Is DTC No. U0401 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Check for DTCs of other systems.
Check if the DTC is set in the ECM (Refer to GROUP 13A - DTC Chart <2.4 L engine>, Refer to GROUP 13B - DTC Chart <3.0 L engine>).
Is the DTC set?
Troubleshoot the DTC (Refer to GROUP 13A - DTC Chart <2.4 L engine>, Refer to GROUP 13B - DTC Chart <3.0 L engine>).
Go to Step 4.
 
STEP 4. Check whether the DTC is set again.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Turn the ignition switch to the "ON" position.
(4) Check if the DTC is set.
Is DTC No. U0401 set?
Replace the ECM (Refer to GROUP 13A - Engine Control Module (ECM) <2.4 L engine>, Refer to GROUP 13B - Engine Control Module (ECM) <3.0 L engine>). Then go to Step 5.
The trouble can be an intermittent malfunction (GROUP 00 - How to use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
 
STEP 5. Check whether the DTC is set again.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Turn the ignition switch to the "ON" position.
(4) Check if the DTC is set.
Is DTC No. U0401 set?
Replace the electric parking brake ECU (Refer to ).
This diagnosis is complete.