Subaru Crosstrek Service Manual: Dtc u0401 invalid data received from ecm/pcm a

DTC DETECTING CONDITION:

Defective data from ECM.

TROUBLE SYMPTOM:

Defective data on CAN communication occurs.

1.CHECK PERFORMING OF BASIC DIAGNOSTIC PROCEDURE.

Was the basic diagnostic procedure performed up to STEP 3?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 2.

Perform the basic diagnostic procedure. Basic Diagnostic Procedure">

2.CHECK DTC.

Check the displayed DTC.

Are DTCs other than U*** displayed?

Perform the diagnosis according to DTC.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 3.

3.CHECK DTC.

Check the displayed DTC.

Is DTC for the bus off or the data no-receive displayed?

Perform the diagnosis according to DTC.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 4.

4.CHECK DTC.

Check the displayed DTC.

Is U0401 a current malfunction?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 5.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 9.

5.CHECK DTC.

1) Turn the ignition switch to OFF.

2) Disconnect the ECM connector.

3) Connect the disconnected connectors.

4) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is U0401 a current malfunction?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 6.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 9.

6.CHECK DTC.

Using the Subaru Select Monitor, read DTC of all the systems. Read Diagnostic Trouble Code (DTC)">

Is the engine data abnormal detected in several modules?

Replace the ECM. Engine Control Module (ECM)">

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 7.

7.REPLACE MODULE.

1) Replace the ECM.

2) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is U0401 a current malfunction?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 8.

System is normal.

8.CHECK MODULE.

1) Reinstall the ECM.

2) Replace the module that the DTC has been detected.

3) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is U0401 a current malfunction?

Replace the ECM. Engine Control Module (ECM)">

System is normal.

9.CHECK HARNESS.

1) Shake the harness, and check for poor contact.

2) Using the Subaru Select Monitor, read DTC of CAN system. Read Diagnostic Trouble Code (DTC)">

Is U0401 a current malfunction?

Repair the poor contact of harness, or replace the harness.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM “A”">Go to Step 10.

10.CHECK CONNECTOR.

Check the connector used for high speed CAN for poor contact.

Is there poor contact of connector?

Repair the connector that has poor contact, or replace harness.

It is possible that temporary poor communication occurs. Delete the DTC.

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