Subaru Battery Keeps Dying? Here’s What Your Dealer Won’t Tell You

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Subaru Battery Keeps Dying? Here’s What Your Dealer Won’t Tell You (Free Fix May Be Available)

By a Subaru Certified Master Technician with 27 years of experience

Serving Upstate South Carolina Subaru owners at Fairway Subaru in Greenville

If your Subaru battery keeps dying, you’re not alone — and you might be entitled to a free fix or even cash reimbursement through a warranty extension that most owners never hear about.

I’ve been a Certified Master Technician at Fairway Subaru in Greenville, SC for over 27 years. In that time, I’ve seen hundreds of customers come in frustrated, having already paid for jump-starts, roadside assistance, and replacement batteries — not knowing that Subaru had quietly extended the warranty to cover the exact issue draining their battery.

Here’s everything you need to know.

Why Your Subaru Battery Keeps Dying

The most common cause of mysterious battery drain in Subarus built between 2015 and 2020 isn’t a bad battery at all. The real culprit is a small module called the Data Communications Module (DCM) — part of the Subaru STARLINK system.

The DCM is supposed to stay mostly dormant when the car is off, but a software defect causes it to “wake up” repeatedly and attempt to connect to cellular towers. Every time it wakes up, it draws power. Over days or weeks of sitting, this parasitic electrical draw kills even a perfectly healthy battery.

The result? You walk out to a dead car, call for a jump, and assume your battery is just old. Many owners in the Greenville SC area replace the battery one, two, or even three times before anyone figures out the real problem.

Affected models include:
– 2015–2020 Subaru Outback
– 2015–2020 Subaru Forester
– 2015–2020 Subaru Legacy
– 2015–2020 Subaru WRX
– 2019–2020 Subaru Ascent

The Warranty Extension Most Owners Don’t Know About

Here’s where it gets important: Subaru extended the warranty on this exact issue to 8 years / 150,000 miles from the original warranty start date.

That means if you own one of the vehicles listed above and are still within that window, Subaru is required to fix it — for free. Depending on what they find, they will either:

  • Replace the faulty DCM module (if you have an active STARLINK subscription), or
  • Bypass the DCM entirely (if you don’t have an active subscription)

They will also cover the cost of charging or replacing a battery that was drained as a direct result of this defect.

How to Claim It

  1. Call Fairway Subaru’s service department in Greenville at your earliest convenience and tell them you’re experiencing parasitic battery drain and want to know if your vehicle is covered under the DCM warranty extension.
  2. Give them your VIN number — they can look up your vehicle’s eligibility instantly.
  3. If you’ve already paid for jump-starts, towing, or a replacement battery due to this issue, ask about reimbursement. A class action settlement was reached that may entitle you to cash back for past expenses.

Pro tip: Write down the name of the service advisor you speak with and ask them to note the concern in writing before your appointment. This protects you if there’s any dispute.

What If My Warranty Has Expired?

If you’re outside the 8-year/150,000-mile window, you still have options.

Option 1: Independent shop diagnosis
A good independent mechanic can perform a parasitic draw test with a basic multimeter. This test measures how much current the car draws with everything off. Normal draw is around 20–50 milliamps. If your Subaru is pulling 200+ milliamps, something is staying awake that shouldn’t be.

Option 2: Replace the battery with a higher-capacity unit
If the DCM is still causing a minor draw but you’re out of warranty, switching to a higher cold-cranking-amp (CCA) battery can reduce how often the issue manifests. It doesn’t fix the root cause, but it buys you time.

Here are two reliable options available on Amazon that fit most affected Subaru models:

Option 3: A portable jump starter in your car
Until the issue is resolved, a compact lithium jump starter is cheap insurance. Many Subaru owners in Greenville SC keep one in the trunk. A reliable option like the NOCO Boost Plus GB40 (affiliate link) can jump-start a dead battery in seconds without needing another vehicle.

How to Tell If the DCM Is Your Problem

Here are the signs that the DCM (and not an aging battery) is your actual issue:

  • Battery dies after 3–5 days of not driving — normal batteries shouldn’t die this fast
  • Newly replaced battery dies within weeks or months
  • Battery warning light comes on intermittently
  • Jumpstart works fine but the car dies again soon after
  • No interior lights left on, no door ajar — no obvious reason for the drain

If you recognize this pattern, don’t waste money on another battery. Call the dealership first and ask about the DCM warranty extension.

What I See at the Dealership

In my 27 years working on Subarus at Fairway Subaru, the battery drain issue is one of the most frustrating for customers — because it’s one of the most misdiagnosed. Many shops simply replace the battery without ever finding the real cause.

When a customer comes in with a “dead battery” complaint on a 2015–2020 Subaru, the first thing I do is check the DCM draw. It takes about 15 minutes to identify. In the majority of cases, that’s the problem.

What makes this especially frustrating is that Subaru quietly issued the warranty extension — they didn’t send letters to every affected owner. That means thousands of Upstate South Carolina Subaru owners and people across the country have paid out of pocket for a problem they were entitled to have fixed for free.

If this sounds like your situation, make that call to Fairway Subaru in Greenville today.

Summary: Your Action Steps

  1. Check if your vehicle is on the affected list (2015–2020 Outback, Forester, Legacy, WRX, or 2019–2020 Ascent)
  2. Call Fairway Subaru in Greenville, SC and ask about the DCM parasitic draw warranty extension
  3. Bring your VIN — they can check eligibility in seconds
  4. Ask about reimbursement if you’ve already paid for battery replacements or jump-starts related to this issue
  5. If out of warranty, consider a higher-capacity replacement battery or keep a portable jump starter on hand

Book Your Battery Inspection at Fairway Subaru Greenville

If you’re experiencing battery drain symptoms on your Subaru, don’t wait — the warranty extension has a deadline based on your vehicle’s original in-service date.

Schedule your free diagnostic at Fairway Subaru in Greenville, SC:

Fairway Subaru
2209 Laurens Rd, Greenville, SC 29607

When you call or visit, mention this article and ask about the DCM warranty extension. Our service team can schedule you for priority attention, and we’ll have your VIN eligibility checked before you arrive. We understand battery drain is frustrating, and we’re here to get you back on the road — potentially at no cost if the warranty covers your vehicle.

Frequently Asked Questions

Q: My car is a 2021 Subaru — does this affect me?
The DCM warranty extension specifically covers 2015–2020 models. The 2021 and newer models have a revised system that does not have the same defect.

Q: My dealer says they don’t know about this warranty extension. What do I do?
Ask them to look up Technical Service Bulletin (TSB) information related to parasitic draw and the DCM module. You can also ask to speak with the service manager. If you’re still getting resistance, call Subaru Customer Advocacy at 1-800-SUBARU3.

Q: I bought a replacement battery before I knew about this. Can I get reimbursed?
Potentially yes. A class action settlement was reached for affected owners. Contact a consumer attorney or search “Subaru battery drain settlement” to check the current status and filing deadlines.

Q: How long does the dealer repair take?
The DCM replacement or bypass is typically completed in a few hours. In most cases you can wait at the dealership or drop the car off for the day.

Have a Subaru question about battery drain or other issues? Drop it in the comments below. I’ll do my best to answer from the service drive perspective at Fairway Subaru.

Disclosure: This article contains affiliate links. If you purchase through these links, we may earn a small commission at no extra cost to you. We only recommend products we’d actually use.

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