ATTENTION:
GENERAL MANAGER

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PARTS MANAGER

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CLAIMS PERSONNEL

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IMPORTANT - All
Service Personnel
Should Read and
Initial in the boxes
provided, right.

SERVICE MANAGER

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© 2025 Subaru of America, Inc. All rights reserved.

SERVICE INFORMATION BULLETIN
APPLICABILITY:

SUBJECT:

2023-26MY Solterra
2026MY Trailseeker
2026MY Uncharted

NUMBER:

15-334-25R

DATE:

12/12/25

Revised:

06/29/26

12-Volt Accessory Battery Depletion and
Parasitic/Dark Current Draw Diagnosis

INTRODUCTION:
This Service Information Bulletin outlines the diagnostic procedures to be followed when identifying
dark current/parasitic draw concerns caused by third-party mobile applications on Solterra vehicles.
A customer may experience 12-Volt battery drain due to unconfirmed causes. Refer to the information
supplied in this bulletin when diagnosing 12-Volt battery drain concerns on Solterra models.
SERVICE PROCEDURE / INFORMATION:
STEP 1: Customer Interview and App Inventory (CRITICAL)
A detailed customer interview MUST be performed by Service Advisor prior to performing
diagnosis. The following information is to be recorded and documented on the repair order.
•

VEHICLE HISTORY: Document the frequency and conditions under which the 12-Volt
battery failure occurs.

•

APP INVENTORY: Create a documented inventory of any third-party mobile applications
the customer is using that interact with the vehicle.
A. Ask the customer specifically if they have provided their SubaruConnect login
credentials (username and password) to any other app or service for purposes such
as:
1. Home charging management (e.g., Optiwatt).
2. Charging network management.
3. Vehicle data monitoring or tracking.
4. Smartwatch/Wearable applications (e.g., Apple Watch companion for Solterra).

CAUTION: VEHICLE SERVICING PERFORMED BY UNTRAINED PERSONS COULD
RESULT IN SERIOUS INJURY TO THOSE PERSONS OR TO OTHERS.
Subaru Service Bulletins are intended for use by professional technicians ONLY. They
are written to inform those technicians of conditions that may occur in some vehicles,
or to provide information that could assist in the proper servicing of the vehicle. Properly
trained technicians have the equipment, tools, safety instructions, and know-how to
do the job correctly and safely. If a condition is described, DO NOT assume that this
Service Bulletin applies to your vehicle, or that your vehicle will have that condition.

Subaru of America, Inc. is
ISO 14001 Compliant
ISO 14001 is the international standard for
excellence in Environmental Management
Systems. Please recycle or dispose of
automotive products in a manner that is friendly
to our environment and in accordance with all
local, state and federal laws and regulations.

Continued...
Bulletin Number: 15-334-25R; Date: 06/29/26

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•

REPAIR ORDER DOCUMENTATION: Note all listed apps/services and the customer’s
response regarding login sharing on the Repair Order.
Category

App Name(s)

Notes on Integration and Parasitic Draw

Optiwatt

Explicitly mentioned in some consumer reports as a known
potential cause. It uses the vehicle’s API (likely by logging in
through the SubaruConnect App credentials) to monitor and
schedule charging, which can lead to excessive polling and
parasitic draw.

Other similar EV telematics/
management apps

Apps with similar functionality to Optiwatt—such as EV Passport,
Smartcar, Chargepoint (for home charging integration if it uses
the vehicle’s API instead of the charger’s), and services like Tesla
charging (though direct integration may be limited to specific
platforms/adapters)—could potentially operate via excessive
polling. Any third-party app requiring the owner’s SubaruConnect
App login should be scrutinized.

Public Charging
Networks

ChargePoint, Electrify
America, Blink, etc.

These apps are primarily used to initiate and pay for public charging and typically communicate with the charging station itself, not
the vehicle’s API, making them low risk for parasitic draw. However, if a user attempts to use a feature to monitor the Solterra’s
charge status through the vehicle’s API via a linked account, the
risk would increase.

Utility/Energy
Monitoring

Emporia Energy (as an
example of an app in the
same category)

While primarily focused on home energy management, if these
apps offer EV-specific features that require vehicle login
credentials to pull live data, they could cause parasitic draw
through frequent wake-ups.

Wearable Tech
Companion

Wear OS (Google) /
watchOS (Apple) companion
apps

The SubaruConnect app has a Wear OS companion. If the watch
app is set to constantly update vehicle status, the frequent polling
from the watch-to-phone-to-car communication could contribute
to a continuous wake-up state, though this is technically an
extension of the OEM app.

EV Smart Charging /
Telematics

EV Smart Charging /
Monitoring

STEP 2: PARASITIC DRAW/DARK CURRENT TESTING (AS REQUIRED)
IMPORTANT: This Step is ONLY required in cases when the customer interview indicates the
use of third-party apps that may be polling the vehicle, or the vehicle has a documented history of
repeated 12-Volt battery failures.
A. Initial Draw Test:
1. Ensure the 12-Volt battery is fully charged or replaced.
2. Follow the procedures in the Subaru Technical Information System (STIS) for parasitic
draw testing, including all setup and required vehicle “sleep” wait times (critical 25
minutes post-vehicle preparation).
Continued...
Bulletin Number: 15-334-25R; Date: 06/29/26

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3. Document: Record the initial parasitic draw level detected on the Repair Order.
B. Draw Threshold:
1. If the measured draw is below 120 mA, proceed to standard (non-parasitic draw-related)
battery system checks.
2. If the measured draw is 120 mA or greater, proceed immediately to Step 3.
STEP 3: ISOLATION OF CUSTOMER DEVICES AND PROFILES (PHONE APP SUSPECT)
If a high parasitic draw (120 mA or greater) is detected, the next step is to eliminate the customer’s
mobile environment before physical component testing.
A. Vehicle Reset:
1. Reconnect the 12-Volt battery.
2. Access the vehicle’s multimedia system.
3. Unpair all customer mobile phones (Bluetooth and Wi-Fi).
4. Delete all customer driver profiles from the vehicle system.
B. Second Parasitic Draw Test (Customer Profile Elimination):
1. Re-perform the parasitic draw test following all STIS setup and wait procedures.
2. Document: Record the parasitic draw level detected with no customer devices paired
and no customer profiles active.
C. Diagnosis:
1. If the draw is now below 120 mA, the root cause is likely a high-polling third-party
application on a customer device. Proceed to Step 4 for confirmation.
2. If the draw is still 120 mA or greater, the parasitic draw is likely internal to the vehicle’s
components or wiring. Proceed to Step 5 for component isolation.
STEP 4: CONFIRMATION OF THIRD-PARTY APP INTERFERENCE (IF DRAW
ELIMINATED)
A. Technician Confirmation Test:
1. Use a known-good testing phone that has ONLY the official SubaruConnect app
installed.
2. Create a new, temporary driver profile and pair the technician’s phone.
3. Ensure the SubaruConnect app is configured to allow full access to location, background
data, and master data.
B. Final Parasitic Draw Test (Technician Profile):
1. Re-perform the parasitic draw test following all STIS setup and wait procedures.
2. Document: Record the parasitic draw level using the technician’s phone, ensuring it is
only paired with SubaruConnect.
C. Conclusion & Repair Order Finalization:
1. If the draw remains below 120 mA, the diagnosis is confirmed: The customer’s 12-Volt battery
depletion is caused by an excessive polling rate from a third-party application using the
SubaruConnect API.

Continued...
Bulletin Number: 15-334-25R; Date: 06/29/26

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2. Advise the customer to uninstall the problematic app(s) or revoke their API access.

STEP 5: STANDARD COMPONENT ISOLATION (IF DRAW IS STILL CURRENT)
1. If, at the end of Step 3 (Second Parasitic Draw Test), the draw is still 120 mA or greater,
then proceed with the standard STIS procedures for component isolation (e.g., fuse
pulling, fuse voltage drop testing, and component disconnection).
2. R/O Documentation: In addition to the inventory and draw readings, the technician must
document the root cause indication (e.g., “Telematics Control Unit (TCU) faulty”) and
the value of the parasitic draw post-component replacement to confirm the repair.
WARRANTY / CLAIM INFORMATION:
There have been no changes made to the Labor Time Guide regarding these procedures.
IMPORTANT REMINDERS:
•

SOA strongly discourages the printing and/or local storage of service information as previously
released information and electronic publications may be updated at any time.

•

Always check for any open recalls or campaigns anytime a vehicle is in for servicing.

•

Always refer to STIS for the latest service information before performing any repairs.

Bulletin Number: 15-334-25R; Date: 06/29/26

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