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Subaru Outback: Parasitic battery drain leaving the car unable to start

Parasitic battery drain leaving the car unable to start is a common electrical fault on the Subaru Outback on the 2021 onward cars, and we rate it major. Putting it right costs ≈A$320 to ≈A$3,500 at independent workshop rates, shown as an approximate guide in Australian dollars. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 34 documented faults on the Subaru Outback.

Vehicle
Subaru Outback
Years
2021 onward
Fuel
petrol
Gearbox
cvt
System
Electrical

This page covers the Subaru Outback as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Subaru Outback faults34 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the 12V battery yet. We would rather show none than show a picture of a different part.

What goes wrong

BT Outback owners frequently report the 12V battery going flat, sometimes within days of the car sitting, leaving it unable to start. Documented parasitic draws on this generation include a faulty rear power-tailgate latch module holding a current draw, and the telematics/StarLink module staying awake and 'phoning home'. The wider Subaru StarLink data-communication-module 3G battery-drain issue and its class-action settlement primarily cover 2015-2020 vehicles, but 2021-2022 cars show the same real-world drain complaints from these other sources. Repairs can be as simple as a battery replacement or as involved as replacing the rear-hatch module with several hours of diagnosis and labour.

What you would notice

  • Car will not start after sitting a few days; battery reads flat
  • Repeated jump-starts or battery replacements needed
  • Intermittent electrical warnings or a dead key-fob interior response
  • Power tailgate behaving erratically or a measurable parasitic current draw

How to check it

Where to look. 12V battery and grounds under the bonnet; rear power-tailgate latch module; telematics/DCM behind the dash

Ask how old the current battery is and how often it has been replaced; if possible, check the resting parasitic draw with a clamp meter after the car has fully gone to sleep (a healthy draw is small, tens of milliamps, not amps). Operate the power tailgate repeatedly to check the latch module, and review service history for battery or DCM-related repairs.

Parts involved: 12V battery.

What it costs to put right

≈A$320 to ≈A$3,500 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “How many times has the battery been replaced, and has anyone measured a parasitic drain?”
  • “Has the rear power-tailgate latch module or the telematics module ever been replaced?”
  • “Does the car reliably start after being parked for a week?”

Now check the Subaru Outback you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

Subaru Outback buyer questions

Is parasitic battery drain leaving the car unable to start serious on a Subaru Outback?

We rate it major and common on the Subaru Outback. BT Outback owners frequently report the 12V battery going flat, sometimes within days of the car sitting, leaving it unable to start. Documented parasitic draws on this generation include a faulty rear power-tailgate latch module holding a current draw, and the telematics/StarLink module staying awake and 'phoning home'. The wider Subaru StarLink data-communication-module 3G battery-drain issue and its class-action settlement primarily cover 2015-2020 vehicles, but 2021-2022 cars show the same real-world drain complaints from these other sources. Repairs can be as simple as a battery replacement or as involved as replacing the rear-hatch module with several hours of diagnosis and labour.

How much does it cost to fix on a Subaru Outback?

≈A$320 to ≈A$3,500 at independent workshop rates, shown as an approximate guide in Australian dollars. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Subaru Outback years are affected?

Our research records this fault on the 2021 onward Subaru Outback. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Ask how old the current battery is and how often it has been replaced; if possible, check the resting parasitic draw with a clamp meter after the car has fully gone to sleep (a healthy draw is small, tens of milliamps, not amps). Operate the power tailgate repeatedly to check the latch module, and review service history for battery or DCM-related repairs. Look here: 12V battery and grounds under the bonnet; rear power-tailgate latch module; telematics/DCM behind the dash