Why Subaru Batteries Are Dying All Across The Country

“Hi David! Car question for you. My battery died and needs to be replaced,” my friend texted me the other week about her 2019 Subaru Outback. AAA had apparently told her she needed to buy an AGM battery or she’d see premature failure, but there were no AGMs available nearby. “He… said that the [standard] battery would only last a year,” my friend texted me in reference to the AAA installation specialist. “He says bc of the auto start/stop feature it will drain too fast.” I advised her to not worry about it, and just have a standard battery installed. She followed my advice. A few days later I received this text: “Omg, my car is dead… again ????” This confused me.

Had I led my friend astray? Had her car’s start/stop starter motor unduly stressed her cheap new battery? I had her text me a photo of her old battery; it wasn’t anything special — just a regular ol’ battery manufactured by Johnson Controls like so many of the others. I googled Subaru Outback 3.6R start/stop, and found this thread — apparently her car doesn’t even have start/stop! So her basic battery should have lasted three to six years, no problem, even in the chilly Rockies.

“Sounds like you have a phantom drain of some sort,” I responded. Something was killing her battery overnight; I asked her if she’d left a dome light on or perhaps the headlights. She told me that, with 99% certainty, she had not. Hmm. Sounded to me like the vehicle needed to be taken into a shop; something was wrong with the electrical system. I did some Googling and found this thread on Reddit:

Included in that Reddit thread is a link to a settlement website titled “Subaru Battery Settlement,” which states on its front page:

A class action lawsuit was filed against Subaru of America, Inc. (“SOA”) and Subaru Corporation (“SBR”), collectively the “Defendants” or “Subaru.” The lawsuit alleges that the Settlement Class Vehicles suffer from a design defect in some vehicles that can cause battery drain; and that Defendants have violated certain consumer statutes and breached certain warranties. The lawsuit seeks certification of a nationwide class of present and former purchasers and lessees of Settlement Class Vehicles to pursue these claims.

Defendants deny the case claims. Defendants maintain that the Settlement Class Vehicles are not defective and that the Settlement Class Vehicles function(ed) in a proper manner, were properly designed, manufactured, distributed, marketed, advertised, warranted, and sold. Defendants claim that they did not violate any warranties, statutes, or laws. In the instances in which such repairs have been necessary, Defendants maintain that they have provided warranty coverage where appropriate.

I sent this to my friend. She replied: “If this is a known issue shouldn’t they do a recall or something?”

Fast forward just a couple of days, and — almost as if the company were dropping eaves on our conversation — received this notice in the mail from Subaru:

“Affected vehicles are equipped with a DCM and may experience a dead battery resulting from the DCM continually trying to access the cellular network due to deterioration of the internal memory,” Subaru writes in its notice titled “Warranty Extension for the Telematics Data Communications Module (DCM) for certain 2019 MYLegacy, Outbacks vehicles and 2019-2021 MY WRX/STI vehicles sold or leased in the United States.”

Subaru is warrantying all affected cars for a year from this notice, or for 8 years and 150,000 miles from the vehicle’s warranty start date. The company will either replace the faulty DCM if the owner has an active STARLINK subscription (STARLINK is a multimedia subscription that connects the car to the internet, allowing you to track the car, lock and unlock doors, make calls using the onbooard SOS button, and more), or they’ll bypass the DCM for those without an active STARLINK subscription. Subaru will also pay to charge/replace a battery drained as a result of the DCM failure.

Here’s the wild thing. The above notice isn’t the only DCM-related warranty-extension Subaru has sent out recently. In late February, Subaru sent out a similar letter for owners of 2016-2018 Legacies, Outbacks, Imprezas, Crosstreks, and Foresters, as well as 2017 to 2017 Subaru WRXs:

“In response to some customer concerns of a dead battery resulting from the DCM continually trying to access the 3G cellular network, which is no longer available, the extension will cover this concern should a customer encounter it during the warranty extension period,” Subaru writes about its eight-year, 100,000-mile warranty on the DCM. The notification will also give those outside of those constraints a single year from this notice to replace the DCM free of charge.

“Affected vehicles are equipped with a DCM and may experience a dead battery as a result of the DCM continually trying to access the retired 3G cellular network and have not received a previous DCM update,” the notice continues.

Subaru has an entire page on its website titled “3G Network Retirement” in which it states that customers had between mid-March of 2021 and February of 2022 to bring their old 3G STARLINK systems into a dealer to be replaced with a 4G system for free. From that website:

STARLINK^® Safety & Security – 3G Network Retirement

STARLINK Safety and Security connected services rely on a wireless connection, and in some older model year Subaru vehicles, these services use a 3G network. In February 2022, the current wireless provider has elected to retire this 3G network, which will affect services such as Automatic Collision Notification, SOS Emergency Assistance, and remote vehicle features in those affected vehicles.

Subaru retailers are offering a complimentary update for affected vehicles that have an active STARLINK Safety and Security subscription. This update will allow continued access to these important STARLINK Safety and Security services. If an affected vehicle is not updated before the 3G network retirement date, the subscription will be canceled.

If you didn’t update your STARLINK, Subaru writes on that website, the results would be: “You will lose access to services such as Automatic Collision Notification, SOS Emergency Assistance, Stolen Vehicle Recovery and Remote Features such as locking and unlocking your Subaru vehicle.” It doesn’t seem like Subaru anticipated “your car will keep trying to connect, even while you’re sleeping, and your battery will drain.”

How exactly this happens, I’m unsure, but this post on Hacker News by someone with a username “siftrics” states:

STARLINK intermittently tries to phone home by hitting 3G towers.

Now that 3G is shutting down, the digital communications module (DCM) gets stuck in an infinite loop of

1. Phone home, expending battery charge 2. Fail, because 3G doesn’t work anymore 3. Go back to step 1

This effectively remotely drains the battery of every Subaru Outback built between 2015 and 2020.

Even if you drive your car every day, its battery will die and you won’t be able to start it.

The internet is filled with Subaru-dead-battery posts, demonstrating how widespread this issue really is. Here are a couple of Reddit posts:

There are plenty more posts on Reddit:

And there are many on Subaru Forums:

And my coworker Jason even got this text message from a friend:

Yikes.

While I can’t know for sure that my friend’s battery drain problem is a result of the first DCM problem (I’m betting it is), there are clearly lots of folks dealing with both of these, and it’s good on Subaru for sending those noticse out and making them right. [Ed note: Maybe I’m onto something? – MH]