Code No. U0401:
Engine (CAN message)
caution |
- If there is any
problem in the CAN bus lines, an incorrect diagnosis 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.
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OPERATION
Engine-related signals are sent or received to and from between electric parking brake
ECU and engine ECU via CAN bus lines.
DIAGNOSIS CODE SET CONDITIONS
The diagnosis code 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.
PROBABLE CAUSES
- 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
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use the M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Go to Step 3.
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Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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Q.
Is diagnosis code No. U0401 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Use M.U.T.-III to confirm a diagnosis code of other systems.
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Check if the diagnosis code is set in the engine ECU (4B1: Refer to GROUP 13A - Diagnosis
Code Chart, 6B3: Refer to GROUP 13B - Diagnosis Code Chart, 4N1: Refer to GROUP 13D - Diagnosis
Code Chart).
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Q.
Is the diagnosis code set?
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Troubleshoot the engine ECU diagnosis code (4B1: Refer to GROUP 13A - Diagnosis
Code Chart, 6B3: Refer to GROUP 13B - Diagnosis Code Chart, 4N1: Refer to GROUP 13D - Diagnosis
Code Chart).
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Go to Step 4.
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STEP 4. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the LOCK (OFF) position.
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(3)Turn the ignition switch to the ON position.
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(4)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. U0401 set?
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Replace the engine ECU (4B1: Refer to GROUP 13A - Engine-ECU, 6B3: Refer
to GROUP 13B - Engine-ECU, 4N1: Refer to GROUP 13D - Engine-ECU). Then go
to Step 5.
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Cope with Intermittent Malfunction).
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STEP 5. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(3)Turn the ignition switch to the "ON" position.
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(4)Check if the diagnosis code is set.
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Q.
Is diagnosis code No. U0401 set?
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Replace the electric parking brake ECU (Refer to ).
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This diagnosis is complete.
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