2019 Subaru Legacy & Outback Wireless Module: The Real Cause of Your Dead Battery
This guide explains the common failure of the Starlink telematics module in the 2019 Subaru Legacy and Outback, which leads to severe battery drain, and details the official fix.
- The primary failure is a parasitic battery drain caused by internal memory corruption in the module.
- Subaru has extended the warranty on this part to 8 years or 150,000 miles; the repair may be free at a dealer.
- Any replacement module (new or used) MUST be programmed by a Subaru dealer to function.
- Verify the part number matches your car's audio system (base or Harman Kardon) before buying a used part.
Known Issues for 2019 Legacy & Outback
The single most significant issue with the wireless communication module (DCM) in the 2019 Subaru Legacy and Outback is a defect that causes a severe parasitic battery drain. This problem is officially acknowledged by Subaru and is distinct from a similar issue in older models related to the 3G network shutdown.
For these 2019 vehicles, the failure is due to "internal memory corruption" within the DCM. This corruption prevents the module from entering its low-power sleep mode after the car is turned off. Instead, it gets stuck in an active loop, continuously drawing power from the battery. This constant power draw, often over 400 milliamps, is enough to completely drain a healthy battery in just one to three days.
Subaru's Official Response: Warranty Extension and TSB
In response to widespread complaints, Subaru of America issued Technical Service Bulletin (TSB) 15-318-24R and extended the warranty for the Data Communication Module.
- Warranty Extension: The warranty on the DCM is extended from the original 3 years/36,000 miles to 8 years or 150,000 miles, whichever comes first.
- The Fix: The official repair depends on whether you have an active Starlink subscription. If the DCM is found to be the cause of the battery drain, the dealer will replace the module at no cost under this warranty extension. For a period, if parts were unavailable, dealers would install a "DCM Bypass Box" (Part No. 86229AL400) for non-subscribed vehicles to restore audio functions while disabling the faulty module. As of early 2025, replacement DCMs are available, and customers who previously received a bypass box can have a new DCM installed.
Pro Tip: If you are experiencing a dead battery, contact a Subaru dealer and reference TSB 15-318-24R or the DCM Warranty Extension. The diagnosis and replacement should be covered even if your vehicle is outside of its original basic warranty.
Symptoms of a Failing Wireless Communication Module
A failing DCM will present several distinct symptoms, almost all related to the parasitic power drain.
- Dead Battery: The most common symptom is a battery that dies after the car sits for 1-3 days. You may find yourself needing to jump-start the vehicle frequently.
- Slow Engine Crank: Before the battery dies completely, you may notice the engine turns over more slowly than usual when you try to start it.
- Red SOS Light: The overhead console may show a solid red light over the "SOS" button, indicating a fault in the telematics system.
- Starlink System Inoperative: You may see errors on the infotainment screen related to telematics, and features like remote start or the MySubaru app will not work.
- Loss of Audio/Bluetooth (If Fuse is Pulled): Some owners temporarily fix the battery drain by pulling the DCM fuse in the fuse box. This will stop the drain but also typically disables the front speakers, Bluetooth microphone, and hands-free calling, as these functions are routed through the DCM.
Buying a Used Wireless Communication Module
Buying a used DCM can save you a significant amount of money, but it comes with critical considerations. This is not a simple plug-and-play part.
Warning: A replacement Wireless Communication Module, whether new or used, MUST be programmed and registered by a Subaru dealer. An independent mechanic or locksmith cannot perform this service. The process involves pairing the module to your car's VIN and activating its internal SIM card with the cellular network.
How to Ensure Compatibility
- Match the Part Number Exactly: There are different modules for vehicles with the base audio system versus those with the premium Harman Kardon (HK) audio system. Do not install a module from an HK car into a non-HK car, or vice-versa. Check the number on your original module before ordering a replacement.
- Known Part Numbers:
- 86222AL11A / 86229AL11A: These are common part numbers for this generation.
- 86229AL21A: This is a superseding part number specifically listed for vehicles with the Harman Kardon audio system. It replaces several earlier versions, including 86229AL11A.
- Physical Inspection: When you receive the used module, inspect the casing for any signs of physical damage or water intrusion. Check that all connector pins are straight and free of corrosion.
Replacement Cost Breakdown
The cost to fix this issue can vary dramatically depending on whether it's covered by Subaru's warranty extension.
| Item | Estimated Cost | Notes |
|---|---|---|
| New OEM Module (Dealer Price) | $800 - $1,100 | Part cost only. One owner reported a dealer quote of $1100 for the part and labor, which was covered by Subaru. |
| Used OEM Module | $50 - $150 | Price from online marketplaces like eBay. Remember to factor in the cost of dealer programming. |
| Shop Labor (Installation) | $100 - $200 | The physical replacement takes about one hour of labor. The module is located under the radio. |
| Shop Labor (Programming) | $100 - $200 | This is a mandatory step that can only be performed by a Subaru dealer. |
| Total (Out of Pocket w/ Used Part) | $250 - $550 | Includes used part cost + installation + mandatory dealer programming. |
| Total (Under Warranty Extension) | $0 | If your vehicle qualifies, the dealer should replace the faulty DCM at no cost. |
Frequently Asked Questions (FAQ)
Does a used wireless communication module need to be programmed?
Yes, absolutely. A replacement module of any kind (new or used) must be taken to a Subaru dealer for programming and registration. Without this step, the Starlink system, including emergency services, will not function.
Can I just unplug the module to fix the battery drain?
You can, but it has consequences. The easiest way is to pull the fuse for the DCM. This will stop the battery drain, but you will lose your front speakers, hands-free microphone, and all Starlink functions. Some companies sell a bypass harness that restores speaker and mic function while keeping the module disconnected.
Is this problem a safety recall?
No, it is not a safety recall. Subaru is handling this issue through a warranty extension and a Technical Service Bulletin (TSB). They state the issue does not impact the safety of the vehicle, though the loss of automatic collision notification could be considered a safety concern by some.
Will a new battery fix the problem?
No. A new battery is only a temporary fix and will also be drained by the faulty DCM within a few days. The root cause is the module itself, which must be replaced or disconnected to permanently solve the power drain.
Technical Specifications
OEM Part Numbers: 86222AL11A 86229AL11A 86229AL21A
Also known as the Data Communication Module (DCM). Located under the radio head unit. Contains a cellular transceiver and GPS receiver for the Subaru Starlink system.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Subaru Legacy:
- Subaru Outback:
- 🛍️ Shop This Part
- Known Issues for 2019 Legacy & Outback
- Subaru's Official Response: Warranty Extension and TSB
- Symptoms of a Failing Wireless Communication Module
- Buying a Used Wireless Communication Module
- How to Ensure Compatibility
- Replacement Cost Breakdown
- Frequently Asked Questions (FAQ)
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