Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2025 Subaru Outback BaseFACTORY OEM SERVICE PROCEDURE
Module Registration (Update & Verification)
| Error message | Cause | Corrective action |
|---|---|---|
| Diagnostic Communication Error. End processing An Error occurred in the following ECUs. ECM***, ECM***••• | Attempted to communicate with the corresponding ECM when it was not connected. | Perform the basic diagnosis of the corresponding ECM, and repeat the procedure from the beginning. If the fault is not fixed, replace the corresponding ECM. |
| Attempted to establish communication while the indicated ECM was not able to communicate. | Turn the ignition switch OFF → ON, and then perform the procedure again from the beginning. If the error persists, perform the basic diagnosis for the indicated ECM. If the same error still persists, replace the indicated ECM. | |
| It is not a target vehicle for Unit Registration. End processing. | A central gateway Control Module with a wrong part number which does not support MAC authentication was installed. | Replace the central gateway Control Module with the correct part number and perform registration from the beginning.
NOTE:
The wrongly-installed central gateway Control Module is not affected. It can be used again as a service part for another vehicle.
|
| Attempted to update the key for a wrong vehicle which is not subject to MAC authentication. | No corrective action.
NOTE:
The wrongly-operated vehicle is not affected. It is OK to proceed to the next operation directly.
|
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| Battery voltage is low. Check the condition of the vehicle and try again. End processing. | The vehicle power supply voltage is 10 V or less. (control module for voltage measurement: Central gateway control module) | Perform the diagnosis for LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE . |
| The Ignition is OFF. After confirming that the Ignition is ON, please press the Rerun Button. | Attempted to update or verify the key with the ignition switch OFF. | Perform the procedure again with the ignition switch ON. |
| The Ignition is ON. After confirming that the Ignition is OFF, please press the Rerun Button. | Attempted to continue the key update with the ignition switch ON against the instruction to turn the ignition switch to OFF. | Follow the instructions on the screen. |
| The ignition switch was turned to ON before the instruction to do so was displayed on the screen. | Follow the instructions on the screen. | |
| Error occurred during Upload / Download. End processing Error code: | The key management server cannot perform any processing. | After a while, perform module registration (update and verification) again. |
| Attempted to perform module registration without performing VIN registration. | Perform VIN registration, and perform module registration (update and verification) again. | |
| Timeout has occurred in Upload / Download. End processing. | No response from the key management server or the response time is too long. | After a while, perform module registration (update and verification) again. |
| Failed to update MAC Key. End processing. ECM***: Success ECM***: Failed to update ECM***: Failed to verify the result••• |
Key update failed on the indicated ECM. | Perform the basic diagnosis for the indicated ECM, and then perform the procedure again from the beginning. If the error persists, replace the indicated ECM. |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.