These instructions apply to the Subaru Impreza Mk5 (GK) 2017-Present.
For other models, please choose your vehicle here.
Disconnecting the 12 V battery on a Subaru Impreza (2017–present) — the fifth-generation GK hatch and GT saloon — is something most owners tackle eventually. You might be fitting a fresh battery, laying the car up over a long winter, clearing space to work safely near the airbags or seat-belt pretensioners, or getting back to normal after a jump-start. It’s an easy job as long as you keep to the correct terminal order and give the car a chance to relearn its settings afterwards. On the e-Boxer mild hybrid there is a separate high-voltage battery too, but everything here deals only with the ordinary 12 V battery, which is entirely safe for an owner to work on.
Where the 12 V Battery Is
On the GK Impreza the 12 V battery sits in the engine compartment, in a tray to one side of the boxer engine, usually under a cover or trim panel that lifts or unclips off. Before you start, pick out the two posts: the negative (−) terminal is black and grounds to the body, while the positive (+) terminal is red and normally sits under a hinged plastic guard. On the e-Boxer mild hybrid there is also a high-voltage battery under the boot floor — never touch the orange high-voltage cabling; you only ever work on the 12 V unit under the bonnet.
Before You Start
- Make sure the car is completely off — not in READY on the e-Boxer — and move the keyless fob well away so the system doesn’t wake.
- Turn off the lights, climate, radio and any accessories, and close the doors you don’t need open.
- Note your radio presets and keep the head-unit security code handy if the car uses one.
- Give it a couple of minutes after switching off for the electronics to power down before loosening a terminal.
- Have the correct spanner ready, plus gloves and eye protection.
Disconnecting the Battery
- Confirm everything is off and the fob is away; on the e-Boxer check the car is not in READY.
- Loosen the clamp on the negative (−) terminal first, lift the lead clear and secure it so it can’t fall back onto the post.
- Now remove the positive (+) lead and keep it well away from any bare metal.
- If you’ll be working near the airbags or pretensioners, wait a couple of minutes after disconnecting before starting.
Reconnecting the Battery
- Refit the positive (+) lead first and tighten its clamp fully.
- Reconnect the negative (−) lead last and tighten it the same way.
- Check both clamps are properly snug — a loose terminal causes flickering and phantom faults — then refit the cover.
What You’ll Need to Reset Afterwards
Removing power clears the Impreza’s short-term memory, so a few things settle back over the first drive or need a quick relearn:
- Clock and radio presets — re-enter the time, your stations and the security code if prompted.
- Power windows — if one-touch and anti-pinch stop working, hold each switch fully up and then fully down at the limit to relearn.
- Steering-angle and EyeSight assistance — these recalibrate themselves after a short drive on a clear, well-marked road.
- Start-stop — on cars with idle-stop, the system may sit out the first drive or two while the battery-management resettles before it cycles again.
- A few warning lights may glow briefly and then clear once the relearns finish.
If a Warning Light Stays On or the Car Feels Off
- Re-check both clamps are tight and fully seated — a poor connection mimics many faults.
- Drive the car steadily so the steering-angle and EyeSight systems can finish relearning.
- Repeat the window one-touch relearn if the express up/down still misbehaves.
- Rule out a genuinely flat or worn-out battery, and fit a like-for-like replacement of the correct spec if needed.
- If a light won’t clear, it has stored a code — look it up on autodtcs.com.
Frequently Asked Questions
Where is the battery on a Subaru Impreza (2017 on)?
In the engine compartment, in a tray to one side of the boxer engine and usually under a cover. On the e-Boxer mild hybrid the high-voltage battery is separate, under the boot floor — never touch its orange cabling; you only work on the 12 V unit.
Which terminal do I disconnect first?
The negative (−) terminal comes off first. On the way back you reverse it: positive (+) on first, then negative last. That order keeps a stray spanner from shorting against the body.
What needs resetting afterwards?
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. On idle-stop cars the start-stop may pause for a drive or two while the battery-management resettles.
Does a new 12 V battery need coding on this Impreza?
A correct-spec like-for-like 12 V battery fits straight in without dealer coding. On start-stop cars the battery-management just relearns the new battery over the first few drives, so a standard swap needs no special tool.
Will disconnecting the battery clear fault codes or the service light?
It can clear some temporary codes, but a genuine fault logs again as soon as the car sees it, so it isn’t a fix. The service reminder is a separate counter and normally isn’t reset by a battery disconnect.
Can I jump-start it instead of disconnecting?
Yes — if you only need to get going after a flat battery, a jump-start avoids all the relearns. You only need to disconnect for a battery renewal, long storage, or work around the airbags and pretensioners.
If a warning light stays on after reconnecting, look up the code on autodtcs.com.
Independent guide — not affiliated with Subaru. Always follow your official service manual and safety precautions. Read our full disclaimer.