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DTC U0401: Engine CAN data error
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
  • Before replacing the ECU, ensure that the communication circuit is normal.
 
 
OPERATION
AWD-ECU temporarily limits the AWD functions if an abnormality in the throttle opening angle signal is detected.
 
 
DTC SET CONDITIONS
If the following conditions are met when the system is in operation (always), AWD-ECU gradually switches the control from AWD to AWD AUTO, flashes the AWD/LOCK indicators alternately, and sets DTC U0401.
  • IG1 voltage: 10 V or more
  • Throttle opening angle signal: More than 100%
 
 
TROUBLESHOOTING HINTS
Current trouble
  • Damaged wiring harness and connectors
  • Malfunction of accelerator pedal position sensor
  • Malfunction of crankshaft position sensor
  • Engine control module malfunction
  • AWD-ECU malfunction
Past trouble
  • Refer to "How to treat past trouble" (GROUP 00 - How to Use Troubleshooting/How to Treat Past Trouble ) for proceeding the diagnostics. Diagnose mainly wiring harness or connector failure between the engine control module and the accelerator pedal position sensor or between the engine control module and the crank angle sensor.
 
 
DIAGNOSIS
STEP 1. Scan tool MB991958 CAN bus diagnostics
Use scan tool MB991958 to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting/CAN Bus Diagnostics Table ). Then go to Step 2.
 
STEP 2. Scan tool MB991958 data list
Check the following data list (Refer to ).
  • Item 08: CAN data (Engine)
Is the check result normal?
Go to Step 7.
Go to Step 3.
 
STEP 3. Scan tool MB991958 DTC of other systems
Check if a DTC related to the accelerator pedal position sensor system or the crank angle sensor system is set in the engine control system.
Is the DTC set?
Troubleshoot the engine control system (Refer to GROUP 13A - Troubleshooting/DTC Chart <2.0L Engine> or GROUP 13C - Troubleshooting/DTC Chart <2.4L Engine>).
Go to Step 4.
 
STEP 4. Scan tool MB991958 DTC of other systems
Check if a DTC, which relates to the CAN communication-linked systems below, is set.
  • Meter
    U0401: DTC of engine-related failure information
Is the DTC set?
Go to Step 5.
Go to Step 6.
 
STEP 5. Check whether the DTC is set again.
Is DTC U0401 set?
Replace the engine control module (Refer to GROUP 13A - Engine Control Module <2.0L Engine> or GROUP 13C - Engine Control Module <2.4L Engine>). Then go to Step 7.
A poor connection, open circuit or other intermittent malfunction between the engine control module and the accelerator pedal position sensor, or between the engine control module and the crank angle sensor is suspected (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ). Then to Step 6.
 
STEP 6. Check whether the DTC is set again.
(1) Erase the DTC.
(2) Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Depress the throttle pedal fully.
(4) Check if the DTC is set.
Is DTC U0401 set?
Replace AWD-ECU (Refer to ). Then go to Step 7 .
A poor connection, open circuit or other intermittent malfunction between the engine control module and the accelerator pedal position sensor, or between the engine control module and the crank angle sensor is suspected (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction ).
 
STEP 7. Check whether the DTC is set again.
Is DTC U0401 set?
Diagnose again from Step 1.
The procedure is complete.