Except For C0 Model

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

DTC detecting condition:

Defective keyless access control module
When inaccessible to ROM in keyless access control module.

Trouble symptom:

Engine cannot be started.

CAUTION:

For replacement procedure of keyless access control module, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.
Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION

CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, perform the clear memory of [Engine]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
3. Turn the ignition switch to OFF.
4. Remove and install the battery. Ref. to REPAIR CONTENTS>NOTE>BATTERY>GROUND TERMINAL REMOVAL OR INSTALLATION
5. Turn the ignition switch to ON.
6. Perform ECM registration. Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.
7. After 5 seconds or more elapse, read the DTC of [Engine] using the Subaru Select Monitor. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTIC TROUBLE CODE (DTC)
Is DTC B1577 displayed? (Current code)

Yes : Replace the keyless access control module. Ref. to SECURITY AND LOCKS>KEYLESS ACCESS CONTROL MODULE>REMOVAL

No : Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE:
In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.