For C5

Diagnosis start condition:

Battery voltage is 10 V or more.
The remote engine starter was not used to start the engine.

DTC detecting condition:

Reference code incompatibility between immobilizer control module and ECM

Trouble symptom:

Engine will not start.
The security indicator illuminates.

CAUTION: When the immobilizer control module or ECM is replaced, registration of the immobilizer system is required. For details, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

CONFIRM NUMBER OF REGISTERED IMMOBILIZER KEY .
Confirm the number of registered immobilizer key. Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

Is the number of registration 0?

Yes: Go to 2.

No: Go to 3.
PERFORM IMMOBILIZER SYSTEM REGISTRATION .
Register the immobilizer system. Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

Is registration complete?

Yes: Finish the diagnosis.

No: Go to 3.
PERFORM ECM REGISTRATION .
Perform ECM registration. Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

Is registration complete?

Yes: Finish the diagnosis.

No: Go to 4.
CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, perform the clear memory of [Engine]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
3. Read the DTC of [Engine] using the Subaru Select Monitor. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.5)>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>DIAGNOSTIC TROUBLE CODE (DTC) . Ref. to ENGINE (DIAGNOSTICS) (H4DO(HEV))>DIAGNOSTIC TROUBLE CODE (DTC) .
Are DTCs other than DTC B1571 displayed? (Current malfunction)

Yes: Perform the diagnosis for DTC other than DTC B1571.

No: Go to 5.
PERFORM ECM REGISTRATION .
1. Turn the ignition switch to OFF.
2. Replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>ENGINE CONTROL MODULE (ECM) .
3. Perform ECM registration. Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.
Is registration complete?

Yes: Finish the diagnosis.

No: Refer to "Correspondence table when registration is not possible" in the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume. If the registration still does not work properly, replace the immobilizer control module. Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .