Disconnect and Reconnect the Battery

Sooner or later every Subaru Outback (2015–2019) owner ends up disconnecting the 12 V battery — the fifth-generation BS wagon is no different. You might be renewing a battery that no longer holds charge, putting the car into hibernation over a long winter, freeing up space to work safely around the airbag or seat-belt pretensioner wiring, or recovering after a jump-start that didn’t quite take. None of it is difficult. Work in the right order, respect the terminals, and the Outback wakes back up and relearns its settings cleanly. This guide walks the whole job through and lists exactly what the car forgets so nothing catches you out afterwards.

Where the 12 V Battery Is

On the BS Outback the 12 V battery lives in the engine compartment, sitting in a tray to one side with the boxer engine in the middle. Lift the bonnet and you’ll usually find it tucked under a cover or trim clip that lifts or unclips off to expose the two posts. Take a moment to identify them before you touch anything: the negative (−) terminal wears a black cap or marking and grounds to the body, while the positive (+) terminal is red and normally sits under a hinged plastic guard. Knowing which is which is the whole safety game here, so don’t rush it.

First, a Few Checks

• Switch the ignition fully off and take the key or keyless fob well away from the car so the system doesn’t wake.
• Turn off the lights, climate, radio and anything else that draws current, and close the doors you don’t need open.
• Note down your radio presets and, if your head unit uses a security code, make sure you have it to hand.
• Give it a couple of minutes after switching off for the modules to power down before you loosen anything.
• Have the correct spanner ready, plus gloves and eye protection — a battery can still deliver a hefty spark.

Disconnecting the Battery

1. Confirm everything electrical is switched off and the key is away from the car.
2. Loosen the clamp nut on the negative (−) terminal first, lift the lead clear and tuck it aside so it can’t spring back onto the post.
3. Now loosen and remove the positive (+) lead, and keep it away from any bare metal.
4. If you plan to work near the airbags or seat-belt pretensioners, wait a couple of minutes after disconnecting so any stored energy in those circuits has bled away.

Reconnecting the Battery

1. Refit the positive (+) lead first and tighten its clamp so it can’t move.
2. Reconnect the negative (−) lead last and tighten it the same way.
3. Check both clamps are genuinely snug — a loose terminal causes flickering, no-starts and phantom faults — then refit the cover.

What You’ll Need to Reset Afterwards

Cutting the power wipes the Outback’s short-term memory, so a handful of things settle back over the first drive or need a quick relearn:

• Clock and radio presets — re-enter the time and your stations, and the security code if the head unit asks for one.
• Power windows — if the one-touch and anti-pinch stop working, hold each switch fully up and then fully down at the limit for a second or two to relearn.
• Steering-angle and EyeSight assistance — the driver-assist systems recalibrate themselves after a short drive on a clear, well-marked road.
• Service reminder — usually unaffected by a disconnect, but glance at it once the car is running.
• A few warning lights may glow briefly and then clear themselves once the relearns finish.

If a Warning Light Stays On or the Car Feels Off

• Re-check that both clamps are tight and fully seated — a poor connection mimics all sorts of faults.
• Take the car for a steady drive so the steering-angle and EyeSight systems can finish relearning.
• Repeat the window one-touch relearn if the express up/down still isn’t behaving.
• If the gear lever won’t come out of ‘P’ after a flat battery, use the console emergency release — see our Outback shift-lock release guide.
• Rule out a genuinely tired or flat battery, and if a light won’t clear it has stored a code worth reading.

Frequently Asked Questions

Where is the battery on a Subaru Outback (2015–2019)?

It’s in the engine compartment, sitting in a tray to one side of the boxer engine, usually under a cover or trim that lifts off. Identify the black negative (−) post and the red positive (+) post under its guard before you start.

Which terminal do I disconnect first?

Always the negative (−) terminal first when disconnecting. On the way back the order reverses: positive (+) on first, then negative last. Doing it this way avoids a short if your spanner brushes bodywork.

What needs resetting after I reconnect?

The clock and radio presets, the window one-touch and anti-pinch, and the steering-angle and EyeSight assistance, which resettle over a short drive. Most items relearn on their own; only the windows may need a manual up/down at the limits.

Does a new battery need coding on this Outback?

A like-for-like 12 V battery of the correct size and type is fitted straight in without dealer coding on this generation. Just make sure the replacement matches the original specification so the charging system is happy.

Will disconnecting the battery clear fault codes or the service light?

Disconnecting can clear some temporary trouble codes, but a genuine fault simply logs again as soon as the car sees the problem, so it’s not a real fix. The service reminder is a separate counter and normally isn’t reset by a battery disconnect.

Can I just jump-start it instead of disconnecting?

If you only need to get going after a flat battery, a jump-start is fine and avoids the relearns entirely. You only need to disconnect for a battery renewal, storage, or work near the airbags and pretensioners.

If the lever is stuck in Park afterwards, see our Outback shift-lock release guide, and if a dashboard light refuses to clear you can look up the stored code on autodtcs.com.